diff --git a/.taskcluster.yml b/.taskcluster.yml
new file mode 100644
index 00000000000000..b590d5e1cefb36
--- /dev/null
+++ b/.taskcluster.yml
@@ -0,0 +1,687 @@
+allowPullRequests: collaborators
+tasks:
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-1, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 1 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-2, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 2 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-3, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 3 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-4, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 4 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-5, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 5 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-reftest-6, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome reftest 6 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-wdspec-1, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome wdspec 1 1"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-1, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 1 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-2, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 2 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-3, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 3 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-4, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 4 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-5, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 5 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-6, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 6 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-7, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 7 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-8, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 8 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-9, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 9 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-10, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 10 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-11, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 11 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-chrome-dev-testharness-12, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ chrome testharness 12 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-1, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 1 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-2, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 2 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-3, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 3 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-4, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 4 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-5, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 5 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-reftest-6, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox reftest 6 6"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-wdspec-1, owner: '{{ event.head.user.email
+      }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox wdspec 1 1"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-1, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 1 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-2, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 2 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-3, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 3 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-4, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 4 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-5, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 5 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-6, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 6 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-7, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 7 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-8, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 8 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-9, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 9 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-10, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 10 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-11, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 11 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+- extra:
+    github:
+      branches: [master]
+      events: [push]
+  metadata: {description: '', name: wpt-firefox-nightly-testharness-12, owner: '{{
+      event.head.user.email }}', source: '{{ event.head.repo.url }}'}
+  payload:
+    artifacts:
+      public/results: {path: /home/test/artifacts, type: directory}
+    command: [/bin/bash, --login, -c, ">-\n            ~/start.sh &&\n           \
+        \ cd /home/test/web-platform-tests &&\n            git fetch {{event.head.repo.url}}\
+        \ &&\n            git config advice.detachedHead false &&\n            git\
+        \ checkout {{event.head.sha}} &&\n            ./tools/ci/ci_taskcluster.sh\
+        \ firefox testharness 12 12"]
+    image: harjgam/web-platform-tests:0.5
+    maxRunTime: 5400
+  provisionerId: '{{ taskcluster.docker.provisionerId }}'
+  workerType: '{{ taskcluster.docker.workerType }}'
+version: 0
diff --git a/css/css-align/content-distribution/place-content-shorthand-002.html b/css/css-align/content-distribution/place-content-shorthand-002.html
index 90fbb60dcb18e1..3df998eca6b4f8 100644
--- a/css/css-align/content-distribution/place-content-shorthand-002.html
+++ b/css/css-align/content-distribution/place-content-shorthand-002.html
@@ -8,9 +8,9 @@
 <script src="../resources/alignment-parsing-utils.js"></script>
 <div id="log"></div>
 <script>
-    var values = ["normal"].concat(contentPositionValues, distributionValues, baselineValues);
-    values.forEach(function(alignValue) {
-        values.forEach(function(justifyValue) {
+    var values = ["normal"].concat(contentPositionValues, distributionValues);
+    baselineValues.concat(values).forEach(function(alignValue) {
+        ["left", "right"].concat(values).forEach(function(justifyValue) {
            test(function() {
                checkPlaceShorhandLonghands("place-content", "align-content", "justify-content", alignValue, justifyValue);
            }, "Checking place-content: " + alignValue + " " + justifyValue);
diff --git a/css/css-align/content-distribution/place-content-shorthand-007-ref.html b/css/css-align/content-distribution/place-content-shorthand-007-ref.html
new file mode 100644
index 00000000000000..67727f4fd26fb9
--- /dev/null
+++ b/css/css-align/content-distribution/place-content-shorthand-007-ref.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<style>
+div {
+  width: 400px;
+  height: 400px;
+  background: blue;
+  position: relative;
+}
+span {
+  background: green;
+  width: 200px;
+  height: 200px;
+  position: absolute;
+  bottom: 0;
+  left: 100px;
+}
+</style>
+Should see a green square centered and at the bottom of the blue square.
+<div><span></span></div>
diff --git a/css/css-align/content-distribution/place-content-shorthand-007.html b/css/css-align/content-distribution/place-content-shorthand-007.html
new file mode 100644
index 00000000000000..be954c9712189d
--- /dev/null
+++ b/css/css-align/content-distribution/place-content-shorthand-007.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Box Alignment: place-content shorthand with fallback</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/css-align/#propdef-place-content">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1430622">
+<link rel="match" href="place-content-shorthand-007-ref.html">
+<style>
+div {
+  display: grid;
+  grid: 200px / 200px;
+  width: 400px;
+  height: 400px;
+  background: blue;
+  place-content: end space-evenly;
+}
+span {
+  background: green;
+}
+</style>
+Should see a green square centered and at the bottom of the blue square.
+<div><span></span></div>
diff --git a/css/css-align/resources/alignment-parsing-utils.js b/css/css-align/resources/alignment-parsing-utils.js
index 9084624e994fc8..5c421cb10be3a3 100644
--- a/css/css-align/resources/alignment-parsing-utils.js
+++ b/css/css-align/resources/alignment-parsing-utils.js
@@ -1,5 +1,5 @@
-var selfPositionValues = [ "start", "end", "self-start", "self-end", "left", "right", "center", "flex-start", "flex-end"];
-var contentPositionValues = [ "start", "end", "left", "right", "center", "flex-start", "flex-end"];
+var selfPositionValues = [ "start", "end", "self-start", "self-end", "center", "flex-start", "flex-end"];
+var contentPositionValues = [ "start", "end", "center", "flex-start", "flex-end"];
 var distributionValues = [ "stretch", "space-around", "space-between", "space-evenly"];
 var baselineValues = [ "baseline", "first baseline", "last baseline"];
 
@@ -33,6 +33,10 @@ function checkPlaceShorhandLonghands(shorthand, alignLonghand, justifyLonghand,
     var div = document.createElement("div");
     div.setAttribute("style", shorthand + ": " + alignValue + " " + justifyValue);
     document.body.appendChild(div);
+    if (alignValue === "first baseline")
+        alignValue = "baseline";
+    if (justifyValue === "first baseline")
+        justifyValue = "baseline";
     if (justifyValue === "")
         justifyValue = alignValue;
     assert_equals(div.style[alignLonghand],
diff --git a/css/css-align/self-alignment/place-self-shorthand-002.html b/css/css-align/self-alignment/place-self-shorthand-002.html
index 16f807da8cb1a4..c41f512de7c5ea 100644
--- a/css/css-align/self-alignment/place-self-shorthand-002.html
+++ b/css/css-align/self-alignment/place-self-shorthand-002.html
@@ -8,9 +8,9 @@
 <script src="../resources/alignment-parsing-utils.js"></script>
 <div id="log"></div>
 <script>
-    var values = ["auto", "normal", "stretch"].concat(selfPositionValues, baselineValues);
-    values.forEach(function(alignValue) {
-        values.forEach(function(justifyValue) {
+    var values = ["auto", "normal", "stretch"].concat(selfPositionValues);
+    baselineValues.concat(values).forEach(function(alignValue) {
+        values.concat(["left", "right"]).forEach(function(justifyValue) {
             test(function() {
                 checkPlaceShorhandLonghands("place-self", "align-self", "justify-self", alignValue, justifyValue);
             }, "Checking place-self: " + alignValue + " " + justifyValue);
diff --git a/css/css-align/self-alignment/place-self-shorthand-006.html b/css/css-align/self-alignment/place-self-shorthand-006.html
index 7e420f4a8686f6..c8de2bfa2b8d82 100644
--- a/css/css-align/self-alignment/place-self-shorthand-006.html
+++ b/css/css-align/self-alignment/place-self-shorthand-006.html
@@ -8,9 +8,9 @@
 <script src="../resources/alignment-parsing-utils.js"></script>
 <div id="log"></div>
 <script>
-    var values = ["auto", "normal", "stretch"].concat(selfPositionValues, baselineValues);
-    values.forEach(function(alignValue) {
-        [""].concat(values).forEach(function(justifyValue) {
+    var values = ["auto", "normal", "stretch"].concat(selfPositionValues);
+    values.concat(baselineValues).forEach(function(alignValue) {
+        ["left", "right"].concat(values).forEach(function(justifyValue) {
             var value = (alignValue + " " + justifyValue).trim();
             test(function() {
                 checkPlaceShorhand("place-self", alignValue, justifyValue)
diff --git a/css/css-scoping/slotted-invalidation.html b/css/css-scoping/slotted-invalidation.html
new file mode 100644
index 00000000000000..f8471062e1d0b2
--- /dev/null
+++ b/css/css-scoping/slotted-invalidation.html
@@ -0,0 +1,35 @@
+<!doctype html>
+<title>CSS Test: Style invalidation for ::slotted()</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<link rel="author" title="Rune Lillesveen" href="mailto:futhark@chromium.org">
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/css-scoping/#slotted-pseudo">
+<div id="host">
+  <div>
+    <span></span>
+    <span></span>
+  </div>
+  <div id="slotted">
+    <span></span>
+    <span></span>
+  </div>
+  <div>
+    <span></span>
+    <span></span>
+  </div>
+</div>
+<script>
+test(function() {
+  var root = host.attachShadow({"mode":"open"});
+  root.innerHTML = '<style>.outer ::slotted(#slotted) { background-color: red } .outer .inner::slotted(#slotted) { background-color: green }</style><div id="outer"><slot id="inner"></slot></div>';
+
+  assert_equals(window.getComputedStyle(slotted).backgroundColor, "rgba(0, 0, 0, 0)");
+
+  root.querySelector("#outer").className = "outer";
+  assert_equals(window.getComputedStyle(slotted).backgroundColor, "rgb(255, 0, 0)");
+
+  root.querySelector("#inner").className = "inner";
+  assert_equals(window.getComputedStyle(slotted).backgroundColor, "rgb(0, 128, 0)");
+})
+</script>
diff --git a/css/css-text/astral-bidi/adlam-anti-ref.html b/css/css-text/astral-bidi/adlam-anti-ref.html
new file mode 100644
index 00000000000000..db4c2fdfea2f4b
--- /dev/null
+++ b/css/css-text/astral-bidi/adlam-anti-ref.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Adlam</title>
+    <link href="support/adlam.css" rel="stylesheet">
+    <link href="adlam.html" rel="mismatch">
+</head>
+<body>
+<p><bdo dir="ltr">𞤀𞤁𞤂𞤁𞤄</bdo></p>
+<p>U+1E900 U+1E901 U+1E902 U+1E901 U+1E904</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/adlam-ref.html b/css/css-text/astral-bidi/adlam-ref.html
new file mode 100644
index 00000000000000..d039127044e0bc
--- /dev/null
+++ b/css/css-text/astral-bidi/adlam-ref.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Adlam</title>
+    <link href="support/adlam.css" rel="stylesheet">
+</head>
+<body>
+<p><bdo dir="rtl">𞤀𞤁𞤂𞤁𞤄</bdo></p>
+<p>U+1E900 U+1E901 U+1E902 U+1E901 U+1E904</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/adlam.html b/css/css-text/astral-bidi/adlam.html
new file mode 100644
index 00000000000000..613aa3ce79369c
--- /dev/null
+++ b/css/css-text/astral-bidi/adlam.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Adlam</title>
+    <link href="support/adlam.css" rel="stylesheet">
+    <link href="adlam-ref.html" rel="match">
+    <link href="https://www.unicode.org/roadmaps/smp/" rel="help">
+    <meta name="assert" content="Upper astral RTL range is treated as RTL.">
+</head>
+<body>
+<p>𞤀𞤁𞤂𞤁𞤄</p>
+<p>U+1E900 U+1E901 U+1E902 U+1E901 U+1E904</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/cypriot-anti-ref.html b/css/css-text/astral-bidi/cypriot-anti-ref.html
new file mode 100644
index 00000000000000..66ffc08275915c
--- /dev/null
+++ b/css/css-text/astral-bidi/cypriot-anti-ref.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Cypriot</title>
+    <link href="support/cypriot.css" rel="stylesheet">
+    <link href="cypriot.html" rel="mismatch">
+</head>
+<body>
+<p><bdo dir="ltr">𐠀𐠰𐠦𐠡𐠩</bdo></p>
+<p>U+10800 U+10830 U+10826 U+10821 U+10829</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/cypriot-ref.html b/css/css-text/astral-bidi/cypriot-ref.html
new file mode 100644
index 00000000000000..ad8accd3a095ae
--- /dev/null
+++ b/css/css-text/astral-bidi/cypriot-ref.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Cypriot</title>
+    <link href="support/cypriot.css" rel="stylesheet">
+</head>
+<body>
+<p><bdo dir="rtl">𐠀𐠰𐠦𐠡𐠩</bdo></p>
+<p>U+10800 U+10830 U+10826 U+10821 U+10829</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/cypriot.html b/css/css-text/astral-bidi/cypriot.html
new file mode 100644
index 00000000000000..e8dcbceea240a0
--- /dev/null
+++ b/css/css-text/astral-bidi/cypriot.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Cypriot</title>
+    <link href="support/cypriot.css" rel="stylesheet">
+    <link href="cypriot-ref.html" rel="match">
+    <link href="https://www.unicode.org/roadmaps/smp/" rel="help">
+    <meta name="assert" content="Lower astral RTL range is treated as RTL.">
+</head>
+<body>
+<p>𐠀𐠰𐠦𐠡𐠩</p>
+<p>U+10800 U+10830 U+10826 U+10821 U+10829</p>
+</body>
+</html>
diff --git a/css/css-text/astral-bidi/support/adlam.css b/css/css-text/astral-bidi/support/adlam.css
new file mode 100644
index 00000000000000..56020cae6039c1
--- /dev/null
+++ b/css/css-text/astral-bidi/support/adlam.css
@@ -0,0 +1,9 @@
+@font-face {
+    font-family: "Noto Sans Adlam";
+    font-weight: normal;
+    font-style: normal;
+    src: url("../../../fonts/noto/NotoSansAdlam-hinted/NotoSansAdlam-Regular.ttf") format("truetype");
+}
+p {
+    font-family: "Noto Sans Adlam";
+}
diff --git a/css/css-text/astral-bidi/support/cypriot.css b/css/css-text/astral-bidi/support/cypriot.css
new file mode 100644
index 00000000000000..23fcb7db5d3a82
--- /dev/null
+++ b/css/css-text/astral-bidi/support/cypriot.css
@@ -0,0 +1,9 @@
+@font-face {
+    font-family: "Noto Sans Cypriot";
+    font-weight: normal;
+    font-style: normal;
+    src: url("../../../fonts/noto/NotoSansCypriot-hinted/NotoSansCypriot-Regular.ttf") format("truetype");
+}
+p {
+    font-family: "Noto Sans Cypriot";
+}
diff --git a/css/css-values/calc-ch-ex-lang-ref.html b/css/css-values/calc-ch-ex-lang-ref.html
new file mode 100644
index 00000000000000..e0ac1ead1e5247
--- /dev/null
+++ b/css/css-values/calc-ch-ex-lang-ref.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<style>
+div {
+  width: calc(1ex + 1ch + 1em);
+  height: calc(1ex + 1ch + 1em);
+  background: green;
+}
+</style>
+<div></div>
diff --git a/css/css-values/calc-ch-ex-lang.html b/css/css-values/calc-ch-ex-lang.html
new file mode 100644
index 00000000000000..eb447475d52887
--- /dev/null
+++ b/css/css-values/calc-ch-ex-lang.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: Calc in font-size with ch / ex units across lang changes</title>
+<link rel="help" href="https://drafts.csswg.org/css-values/#ch">
+<link rel="help" href="https://drafts.csswg.org/css-values/#ex">
+<link rel="help" href="https://drafts.csswg.org/css-values/#funcdef-calc">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1431031">
+<link rel="match" href="calc-ch-ex-lang-ref.html">
+<style>
+div[lang] {
+  font-size: calc(1ex + 1ch + 1em);
+}
+</style>
+<div lang="en">
+  <div style="width: 1em; height: 1em; background: green;"></div>
+</div>
diff --git a/css/css-values/calc-rem-lang-ref.html b/css/css-values/calc-rem-lang-ref.html
new file mode 100644
index 00000000000000..a0f6add684a57f
--- /dev/null
+++ b/css/css-values/calc-rem-lang-ref.html
@@ -0,0 +1,6 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<p>You should see a green box twice-the-initial-font-size wide.</p>
+<div style="width: 2em; height: 2em; background: green;"></div>
diff --git a/css/css-values/calc-rem-lang.html b/css/css-values/calc-rem-lang.html
new file mode 100644
index 00000000000000..3994efc003b5a1
--- /dev/null
+++ b/css/css-values/calc-rem-lang.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<html lang="en"><!-- The lang is important! -->
+<meta charset="utf-8">
+<title>CSS Test: Calc with rem and relative units on the root element</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/css-values/#rem">
+<link rel="help" href="https://drafts.csswg.org/css-values/#funcdef-calc">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1431031">
+<link rel="match" href="calc-rem-lang-ref.html">
+<style>
+  html {
+    font-size: calc(1rem + 1em);
+  }
+</style>
+<p style="font-size: initial">You should see a green box twice-the-initial-font-size wide.</p>
+<div style="width: 1em; height: 1em; background: green;"></div>
+</html>
diff --git a/css/cssom-view/elementFromPoint-dynamic-anon-box.html b/css/cssom-view/elementFromPoint-dynamic-anon-box.html
new file mode 100644
index 00000000000000..e0acb90fb8fe76
--- /dev/null
+++ b/css/cssom-view/elementFromPoint-dynamic-anon-box.html
@@ -0,0 +1,44 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: Hit testing on element previously hidden by an anonymous scroll box</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1433591">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+html, body {
+  margin: 0;
+  padding: 0;
+}
+/*
+  Create a hidden scrollbox that occupies the whole viewport, then give it
+  visibility: hidden dynamically. The link previously under the scrollbox
+  should be clickable.
+ */
+.scrollable {
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100vw;
+  height: 100vh;
+  overflow: scroll;
+}
+
+.scrollable .inner {
+  display: table-cell;
+  width: 100vw;
+  height: 100vh;
+}
+</style>
+<div class="scrollable">
+  <div class="inner"></div>
+</div>
+<a href="#">Should be clickable</a>
+<script>
+test(function() {
+  assert_equals(document.elementFromPoint(10, 10).tagName, "DIV",
+                "Should hit the scrollbox contents");
+  document.querySelector('div').style.visibility = "hidden";
+  assert_equals(document.elementFromPoint(10, 10), document.querySelector('a'));
+}, "Link should be clickable after hiding a scrollbox with an anonymous table inside");
+</script>
diff --git a/css/fonts/noto/NotoSansAdlam-hinted/LICENSE_OFL.txt b/css/fonts/noto/NotoSansAdlam-hinted/LICENSE_OFL.txt
new file mode 100644
index 00000000000000..d952d62c065f3f
--- /dev/null
+++ b/css/fonts/noto/NotoSansAdlam-hinted/LICENSE_OFL.txt
@@ -0,0 +1,92 @@
+This Font Software is licensed under the SIL Open Font License,
+Version 1.1.
+
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to
+provide a free and open framework in which fonts may be shared and
+improved in partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply to
+any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software
+components as distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to,
+deleting, or substituting -- in part or in whole -- any of the
+components of the Original Version, by changing formats or by porting
+the Font Software to a new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed,
+modify, redistribute, and sell modified and unmodified copies of the
+Font Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components, in
+Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the
+corresponding Copyright Holder. This restriction only applies to the
+primary font name as presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created using
+the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.
diff --git a/css/fonts/noto/NotoSansAdlam-hinted/NotoSansAdlam-Regular.ttf b/css/fonts/noto/NotoSansAdlam-hinted/NotoSansAdlam-Regular.ttf
new file mode 100644
index 00000000000000..0ab5d995c96402
Binary files /dev/null and b/css/fonts/noto/NotoSansAdlam-hinted/NotoSansAdlam-Regular.ttf differ
diff --git a/css/fonts/noto/NotoSansAdlam-hinted/README b/css/fonts/noto/NotoSansAdlam-hinted/README
new file mode 100644
index 00000000000000..d22876499aa332
--- /dev/null
+++ b/css/fonts/noto/NotoSansAdlam-hinted/README
@@ -0,0 +1,11 @@
+This package is part of the noto project.  Visit
+google.com/get/noto for more information.
+
+Built on 2017-10-24 from the following noto repository:
+-----
+Repo: noto-fonts
+Tag: v2017-10-24-phase3-second-cleanup
+Date: 2017-10-24 12:10:34 GMT
+Commit: 8ef14e6c606a7a0ef3943b9ca01fd49445620d79
+
+Remove some files that aren't for release.
diff --git a/css/fonts/noto/NotoSansCypriot-hinted/LICENSE_OFL.txt b/css/fonts/noto/NotoSansCypriot-hinted/LICENSE_OFL.txt
new file mode 100644
index 00000000000000..d952d62c065f3f
--- /dev/null
+++ b/css/fonts/noto/NotoSansCypriot-hinted/LICENSE_OFL.txt
@@ -0,0 +1,92 @@
+This Font Software is licensed under the SIL Open Font License,
+Version 1.1.
+
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to
+provide a free and open framework in which fonts may be shared and
+improved in partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply to
+any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software
+components as distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to,
+deleting, or substituting -- in part or in whole -- any of the
+components of the Original Version, by changing formats or by porting
+the Font Software to a new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed,
+modify, redistribute, and sell modified and unmodified copies of the
+Font Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components, in
+Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the
+corresponding Copyright Holder. This restriction only applies to the
+primary font name as presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created using
+the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.
diff --git a/css/fonts/noto/NotoSansCypriot-hinted/NotoSansCypriot-Regular.ttf b/css/fonts/noto/NotoSansCypriot-hinted/NotoSansCypriot-Regular.ttf
new file mode 100644
index 00000000000000..6727e13d62857f
Binary files /dev/null and b/css/fonts/noto/NotoSansCypriot-hinted/NotoSansCypriot-Regular.ttf differ
diff --git a/css/fonts/noto/NotoSansCypriot-hinted/README b/css/fonts/noto/NotoSansCypriot-hinted/README
new file mode 100644
index 00000000000000..d22876499aa332
--- /dev/null
+++ b/css/fonts/noto/NotoSansCypriot-hinted/README
@@ -0,0 +1,11 @@
+This package is part of the noto project.  Visit
+google.com/get/noto for more information.
+
+Built on 2017-10-24 from the following noto repository:
+-----
+Repo: noto-fonts
+Tag: v2017-10-24-phase3-second-cleanup
+Date: 2017-10-24 12:10:34 GMT
+Commit: 8ef14e6c606a7a0ef3943b9ca01fd49445620d79
+
+Remove some files that aren't for release.
diff --git a/css/selectors/invalidation/selectorText-dynamic-001.html b/css/selectors/invalidation/selectorText-dynamic-001.html
new file mode 100644
index 00000000000000..c705c2b3e85f59
--- /dev/null
+++ b/css/selectors/invalidation/selectorText-dynamic-001.html
@@ -0,0 +1,24 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: invalidation of class changes when the selector in a rule has changed</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/selectors-4/">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1432850">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+  body { background: green; }
+  .red { background: red; }
+</style>
+<body class="red">
+Should have a green background.
+<script>
+test(() => {
+  document.body.offsetTop;
+  assert_equals(getComputedStyle(document.body).backgroundColor, "rgb(255, 0, 0)");
+  document.body.className = "";
+  document.styleSheets[0].cssRules[1].selectorText = ".bar";
+  assert_equals(getComputedStyle(document.body).backgroundColor, "rgb(0, 128, 0)");
+}, "Style should be recomputed correctly when the selector it depends on changes");
+</script>
+</body>
diff --git a/css/selectors/invalidation/sheet-going-away-001.html b/css/selectors/invalidation/sheet-going-away-001.html
new file mode 100644
index 00000000000000..7b704eca97ff5b
--- /dev/null
+++ b/css/selectors/invalidation/sheet-going-away-001.html
@@ -0,0 +1,26 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: invalidation of class changes when the sheet the style depends on goes away</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/selectors-4/">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1432850">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+  body { background: green; }
+</style>
+<style id="style">
+  .red { background: red; }
+</style>
+<body class="red">
+Should have a green background.
+<script>
+test(() => {
+  document.body.offsetTop;
+  assert_equals(getComputedStyle(document.body).backgroundColor, "rgb(255, 0, 0)");
+  document.body.className = "";
+  style.remove();
+  assert_equals(getComputedStyle(document.body).backgroundColor, "rgb(0, 128, 0)");
+}, "Style should be recomputed correctly when the stylesheet it depends on goes away");
+</script>
+</body>
diff --git a/css/selectors/invalidation/sheet-going-away-002-ref.html b/css/selectors/invalidation/sheet-going-away-002-ref.html
new file mode 100644
index 00000000000000..67841617736730
--- /dev/null
+++ b/css/selectors/invalidation/sheet-going-away-002-ref.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<p style="color: green">
+  Should be green.
+</p>
diff --git a/css/selectors/invalidation/sheet-going-away-002.html b/css/selectors/invalidation/sheet-going-away-002.html
new file mode 100644
index 00000000000000..41778239518d4d
--- /dev/null
+++ b/css/selectors/invalidation/sheet-going-away-002.html
@@ -0,0 +1,23 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: invalidation of class changes when the sheet the style depends on goes away</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://drafts.csswg.org/selectors-4/">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1432850">
+<link rel="match" href="sheet-going-away-002-ref.html">
+<style>
+  p { color: green; }
+</style>
+<style id="style">
+  .red p { color: red; }
+</style>
+<body class="red">
+<p>
+  Should be green.
+</p>
+<script>
+document.body.offsetTop;
+document.body.className = "";
+style.remove();
+</script>
+</body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001-ref.html
index f96f07c3881805..98b4bd95823d4a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001.html
index 3e1819193807e9..62a8ecb355d2b3 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-001.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
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     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
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     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002-ref.html
index 93a027b096ebee..b9bde37740edd8 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002.html
index ad3437473a9dd0..d546bf55394d07 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-002.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003-ref.html
index 383d181c9b45bb..3d4867f617c4bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003.html
index 4ed94d0874a14e..3960f474c9b599 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-003.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004-ref.html
index 3702330bcb1e3f..82399e3accfaf6 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
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 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004.html
index d859af21118ba3..a1b00544f8518a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-004.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
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 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005-ref.html
index d2d5a99a8588d8..8d853a84df64f8 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005.html
index ec491ffe87a3aa..65b744f8b829bc 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-005.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006-ref.html
index 880f25836df13b..f4880c4d68de13 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
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 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006.html
index 1ce890a99d012b..209f0410d08021 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-006.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007-ref.html
index aaac464cda1f35..55a390da0cdb87 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007.html
index 9964af6988d93c..eb2365abbe462d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-007.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008-ref.html
index 14166e151f1bb5..f8b40d27e858f2 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008.html
index 2a8fa4b7c5a75d..6dafc4636f4895 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-008.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
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diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001-ref.html
index 383d181c9b45bb..3d4867f617c4bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
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 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001.html
index f45b5371ac4e2a..e0d37083668202 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-001.html
@@ -71,8 +71,6 @@
     <!-- <content-position>, part 2 -->
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     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
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   <div class="small">
@@ -99,8 +97,6 @@
     <!-- <content-position>, part 2 -->
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     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
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diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002-ref.html
index c1f117e2b61f9f..989d6ac13d5e2e 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002.html
index 755db6cec927d2..9f8ae7f4ce4632 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-rtl-002.html
@@ -71,8 +71,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -99,8 +97,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001-ref.html
index f952c8daa3c046..989d6ac13d5e2e 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001-ref.html
@@ -67,8 +67,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -95,8 +93,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001.html
index 5fa7f7722b3868..456cc59a339da0 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-001.html
@@ -71,8 +71,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -99,8 +97,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002-ref.html
index 492924567abe68..3d4867f617c4bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002-ref.html
@@ -70,8 +70,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -98,8 +96,6 @@
     <!-- <content-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002.html
index 2544032827cee5..f1013db1db0998 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-content-vertWM-002.html
@@ -71,8 +71,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
   <div class="small">
@@ -99,8 +97,6 @@
     <!-- <content-position>, part 2 -->
     <div class="container" style="align-content: flex-start"><div></div></div>
     <div class="container" style="align-content: flex-end"><div></div></div>
-    <div class="container" style="align-content: left"><div></div></div>
-    <div class="container" style="align-content: right"><div></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001-ref.html
index e85089fc921912..6c0f732532d190 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001.html
index ea05c96b0b655e..6aad51819716b7 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-001.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002-ref.html
index c6398ca529e923..c1715dcd64c36f 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002.html
index a45c61d31b00d7..06956ba2cb680f 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-002.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003-ref.html
index 6d08814e35e5f7..d1b2c59990618c 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003.html
index 5af8077ba4c12e..247f5216a8cca5 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-003.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004-ref.html
index 7065861dc8f75f..24fb8a1e7fd4bf 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004.html
index 6f00b15fd0c817..e684dd6bfef15f 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-004.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005-ref.html
index 08501e8411cf76..9d8f4469ac36d7 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005.html
index c5d1f5b619e9a6..1421878e4fbbb7 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-005.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006-ref.html
index 8ad1291144943f..b3df68fab3c181 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006.html
index ee197960853576..aa093438f6bf47 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-006.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007-ref.html
index 25609fc3c8e04b..a5316ce81107a5 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007.html
index b7b1d8a9dd77eb..7721031b7ac436 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-007.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008-ref.html
index 3feea0b3159849..c40a2d75cf31a2 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignEnd"><!--flex-start--></div></div>
     <div class="container"><div class="alignStart"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008.html
index b1fdc92209e38b..6bea8aaa00e0a9 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-008.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001-ref.html
index 4e395aa6683975..75a998e34121bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001.html
index 6c8bc5c781c43c..82120fb52e3c10 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-001.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002-ref.html
index 4e395aa6683975..75a998e34121bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002.html
index 99e171a0f8e412..1b2ff2e320b8b6 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-002.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003-ref.html
index b773df598b5e1d..b48de7e5cb115b 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003.html
index 3bac61b68eac18..498e230f92aaad 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-003.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004-ref.html
index 3fb58426826beb..2ed4a2d798a770 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004-ref.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignEnd"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004.html
index 5588bee71e08a8..c4cb4b5138d5b0 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-rtl-004.html
@@ -65,8 +65,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -91,8 +89,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003-ref.html
index 9cd5fb6e8954e1..75a998e34121bd 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003.html
index a54c7d5f267f44..c340cdc290fce5 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-003.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004-ref.html
index 7787fba0808c8c..a4be517ce0669d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004-ref.html
@@ -68,8 +68,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -94,8 +92,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignEnd"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004.html
index c0ccc9bb7ffad0..5113cdd8ac2347 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-align-self-vertWM-004.html
@@ -66,8 +66,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -92,8 +90,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001-ref.html
index 24935ee0abb426..ec0d6cc41278ce 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001-ref.html
@@ -51,10 +51,16 @@
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
-    <div class="container"><div class="alignEnd"><!--space-between--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-around--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
-    <div class="container"><div class="alignEnd"><!--stretch--></div></div>
+    <div style="display: none">
+      <!--
+        These tests will be valid when
+        https://github.com/w3c/csswg-drafts/issues/1002 is fixed
+      -->
+      <div class="container"><div class="alignEnd"><!--space-between--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-around--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
+      <div class="container"><div class="alignEnd"><!--stretch--></div></div>
+    </div>
     <br>
   </div>
   <div class="small">
@@ -65,10 +71,16 @@
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
-    <div class="container"><div class="alignEnd"><!--space-between--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-around--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
-    <div class="container"><div class="alignEnd"><!--stretch--></div></div>
+    <div style="display: none">
+      <!--
+        These tests will be valid when
+        https://github.com/w3c/csswg-drafts/issues/1002 is fixed
+      -->
+      <div class="container"><div class="alignEnd"><!--space-between--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-around--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
+      <div class="container"><div class="alignEnd"><!--stretch--></div></div>
+    </div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001.html
index e1de7af3b20822..e1c6b79076d540 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-align-content-001.html
@@ -49,10 +49,12 @@
     <div class="container" style="align-content: stretch"><div></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
+    <!--
     <div class="container" style="align-content: space-between flex-end"><div></div></div>
     <div class="container" style="align-content: space-around flex-end"><div></div></div>
     <div class="container" style="align-content: space-evenly flex-end"><div></div></div>
     <div class="container" style="align-content: stretch flex-end"><div></div></div>
+    -->
     <br>
   </div>
   <div class="small">
@@ -63,10 +65,12 @@
     <div class="container" style="align-content: stretch"><div></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
+    <!--
     <div class="container" style="align-content: space-between flex-end"><div></div></div>
     <div class="container" style="align-content: space-around flex-end"><div></div></div>
     <div class="container" style="align-content: space-evenly flex-end"><div></div></div>
     <div class="container" style="align-content: stretch flex-end"><div></div></div>
+    -->
   </div>
 </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001-ref.html
index 21185bcb2d8963..0abf592d6d476d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001-ref.html
@@ -51,10 +51,12 @@
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
-    <div class="container"><div class="alignEnd"><!--space-between--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-around--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
-    <div class="container"><div class="alignStart"><!--stretch--></div></div>
+    <div style="display: none">
+      <div class="container"><div class="alignEnd"><!--space-between--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-around--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
+      <div class="container"><div class="alignStart"><!--stretch--></div></div>
+    </div>
     <br>
   </div>
   <div class="small">
@@ -65,10 +67,12 @@
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
-    <div class="container"><div class="alignEnd"><!--space-between--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-around--></div></div>
-    <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
-    <div class="container"><div class="alignStart"><!--stretch--></div></div>
+    <div style="display: none">
+      <div class="container"><div class="alignEnd"><!--space-between--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-around--></div></div>
+      <div class="container"><div class="alignEnd"><!--space-evenly--></div></div>
+      <div class="container"><div class="alignStart"><!--stretch--></div></div>
+    </div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001.html
index d90dc75971f6c1..88335dca854fcc 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-fallback-justify-content-001.html
@@ -49,10 +49,12 @@
     <div class="container" style="justify-content: stretch"><div></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
+    <!-- TODO: https://github.com/w3c/csswg-drafts/issues/1002
     <div class="container" style="justify-content: space-between flex-end"><div></div></div>
     <div class="container" style="justify-content: space-around flex-end"><div></div></div>
     <div class="container" style="justify-content: space-evenly flex-end"><div></div></div>
     <div class="container" style="justify-content: stretch flex-end"><div></div></div>
+    -->
     <!-- Note: specifically for flex containers, in the justify-content axis,
          "stretch behaves as flex-start (ignoring the specified fallback
          alignment, if any." https://drafts.csswg.org/css-align-3/#distribution-flex -->
@@ -66,10 +68,12 @@
     <div class="container" style="justify-content: stretch"><div></div></div>
     <br>
     <!-- <content-distribution> with explicit "flex-end" fallback -->
+    <!-- TODO: https://github.com/w3c/csswg-drafts/issues/1002
     <div class="container" style="justify-content: space-between flex-end"><div></div></div>
     <div class="container" style="justify-content: space-around flex-end"><div></div></div>
     <div class="container" style="justify-content: space-evenly flex-end"><div></div></div>
     <div class="container" style="justify-content: stretch flex-end"><div></div></div>
+    -->
     <!-- As noted above, the explicit fallback for "stretch" is ignored here. -->
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001-ref.html
index fc450981e75e91..be61c53b491d84 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001.html
index 1d571360a16064..33cec45906af24 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-001.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002-ref.html
index fc450981e75e91..be61c53b491d84 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002.html
index 09073d4fbff856..68025bf739dec8 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-002.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003-ref.html
index d4962697556e5e..f609ed2896af4c 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003.html
index f2801ebdd2ae6d..80c747700d22d6 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-003.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004-ref.html
index d4962697556e5e..f609ed2896af4c 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004.html
index 0f8d330bae32db..6c0f8e4ea685b6 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-004.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005-ref.html
index 807f161247631d..b04e8f2337660a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005.html
index 729ca97327a883..83703c8adc5d41 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-005.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006-ref.html
index 807f161247631d..b04e8f2337660a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006.html
index 83da7de4f1abe0..f30bd06737c529 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-006.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007-ref.html
index 04979dfa7bd2cc..2da4bf974f674b 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007.html
index ad97ac3ce7cdc8..4eef2a7bfd58a0 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-007.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008-ref.html
index 04979dfa7bd2cc..2da4bf974f674b 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignEnd"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008.html
index d6a4074e331382..375e9aadbe0b09 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-008.html
@@ -47,10 +47,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -75,10 +71,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001-ref.html
index 2ccb6b15761efe..2c70fa14a6464d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001.html
index 94df40c0e9788d..5143a56423277f 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-001.html
@@ -48,10 +48,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -76,10 +72,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002-ref.html
index 4cf94716416e55..8901d350f84c19 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002-ref.html
@@ -52,10 +52,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -80,10 +76,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002.html
index f85c7d051e2cf6..d56a25c3c9662a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-rtl-002.html
@@ -48,10 +48,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -76,10 +72,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001-ref.html
index dc9b6da9bbc705..64a85443a4b85a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001-ref.html
@@ -52,10 +52,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -80,10 +76,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001.html
index db4b5b69144bcc..8971b4b9de543a 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-001.html
@@ -48,10 +48,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -76,10 +72,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002-ref.html
index d4fd90e353922f..3e109d01e63c4b 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002-ref.html
@@ -49,10 +49,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
@@ -77,10 +73,6 @@
     <!-- normal -->
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container"><div class="alignStart"><!--space-between--></div></div>
     <div class="container"><div class="alignCenter"><!--space-around--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002.html
index 1eb456d6e0ff7f..59ea15340cbb4f 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/flex-abspos-staticpos-justify-content-vertWM-002.html
@@ -48,10 +48,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
@@ -76,10 +72,6 @@
     <!-- normal -->
     <div class="container" style="justify-content: normal"><div></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container" style="justify-content: baseline"><div></div></div>
-    <div class="container" style="justify-content: last baseline"><div></div></div>
-    <br>
     <!-- <content-distribution> -->
     <div class="container" style="justify-content: space-between"><div></div></div>
     <div class="container" style="justify-content: space-around"><div></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001-ref.html
index e519f2d7afd981..36b570f24580ad 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001-ref.html
@@ -66,8 +66,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -92,8 +90,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001.html
index 02b7a136abf7cc..191d6b84cb6b98 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-001.html
@@ -67,8 +67,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -93,8 +91,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002-ref.html
index eaa1c712d9e621..376e0086f85f19 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002-ref.html
@@ -64,8 +64,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
   <div class="small">
@@ -90,8 +88,6 @@
     <!-- <self-position>, part 2: -->
     <div class="container"><div class="alignStart"><!--flex-start--></div></div>
     <div class="container"><div class="alignEnd"><!--flex-end--></div></div>
-    <div class="container"><div class="alignStart"><!--left--></div></div>
-    <div class="container"><div class="alignStart"><!--right--></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002.html
index 32f90939b7e50c..b9ee7277ab9554 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-align-self-002.html
@@ -66,8 +66,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
   <div class="small">
@@ -92,8 +90,6 @@
     <!-- <self-position>, part 2 -->
     <div class="container"><div style="align-self: flex-start"></div></div>
     <div class="container"><div style="align-self: flex-end"></div></div>
-    <div class="container"><div style="align-self: left"></div></div>
-    <div class="container"><div style="align-self: right"></div></div>
     <br>
   </div>
 </body>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001-ref.html
index 6d197e490fe69c..0b87de98813cc3 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001-ref.html
@@ -53,10 +53,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001.html
index 99cfcbb9b4e654..3fa15f1d645e90 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-001.html
@@ -54,10 +54,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -80,10 +76,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002-ref.html
index 741a795f20eeb2..592cf8933c00ed 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002-ref.html
@@ -51,10 +51,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -77,10 +73,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002.html
index b82d308af1b7e1..8db71d352218c5 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-002.html
@@ -53,10 +53,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001-ref.html
index 78d621219ab0fd..2fcc585581a192 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001-ref.html
@@ -54,12 +54,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignStart"><!--stretch--></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignStart"><!--baseline--></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignEnd"><!--last baseline--></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignCenter"><!--center--></div>
@@ -94,12 +88,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignStart"><!--stretch--></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignStart"><!--baseline--></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignEnd"><!--last baseline--></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignCenter"><!--center--></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001.html
index fdd4f6220be512..ad392ccc2138b4 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-001.html
@@ -53,12 +53,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: stretch"></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: baseline"></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: last baseline"></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: center"></div>
@@ -93,12 +87,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: stretch"></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: baseline"></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: last baseline"></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: center"></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002-ref.html
index a1d4e8163fd943..65badb02a48a34 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002-ref.html
@@ -52,12 +52,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignStart"><!--stretch--></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignStart"><!--baseline--></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignEnd"><!--last baseline--></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignCenter"><!--center--></div>
@@ -92,12 +86,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignStart"><!--stretch--></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignStart"><!--baseline--></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                class="alignEnd"><!--last baseline--></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><img src="support/colors-8x16.png"
                                 class="alignCenter"><!--center--></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002.html
index 61c1b97b51f840..c17471029184ec 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-img-002.html
@@ -52,12 +52,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: stretch"></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: baseline"></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: last baseline"></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: center"></div>
@@ -92,12 +86,6 @@
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: stretch"></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: baseline"></div>
-    <div class="container"><img src="support/colors-8x16.png"
-                                style="justify-self: last baseline"></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><img src="support/colors-8x16.png"
                                 style="justify-self: center"></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001-ref.html
index 8e5db1efc59b81..a2899e07feaa7e 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001-ref.html
@@ -53,10 +53,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001.html
index 18e024bf2e8e49..a0a57aee0a8b4d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-001.html
@@ -54,10 +54,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -80,10 +76,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002-ref.html
index c7176a7c21025a..06312f500b5228 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002-ref.html
@@ -53,10 +53,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002.html
index d7e510e1b5eee5..a309859b5b4821 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-002.html
@@ -55,10 +55,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -81,10 +77,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003-ref.html
index b38590c8021c41..9c243ac5f362b4 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003-ref.html
@@ -51,10 +51,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -77,10 +73,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003.html
index 2224ff684aff7e..19cf377cad20ef 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-003.html
@@ -53,10 +53,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004-ref.html
index 1ebc9e62c976a5..3cbad644b495cf 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004-ref.html
@@ -51,10 +51,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -77,10 +73,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004.html
index a22fdc24fb7228..f8170a80d37646 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-rtl-004.html
@@ -54,10 +54,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -80,10 +76,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001-ref.html
index 9fff3eabcc0860..0b40e42550b5e3 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001-ref.html
@@ -55,10 +55,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -81,10 +77,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001.html
index 1bc2a5c33869d9..d3ce4007d91c63 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-001.html
@@ -53,10 +53,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002-ref.html
index 9fff3eabcc0860..0b40e42550b5e3 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002-ref.html
@@ -55,10 +55,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -81,10 +77,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002.html
index 7b72c6aaeb17bf..03078a6b44836d 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-002.html
@@ -54,10 +54,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -80,10 +76,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003-ref.html
index 15507845661d58..ecc148a3215a09 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003-ref.html
@@ -53,10 +53,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003.html
index 582262bd3deb17..e6a712d00dae23 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-003.html
@@ -52,10 +52,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -78,10 +74,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004-ref.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004-ref.html
index 15507845661d58..ecc148a3215a09 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004-ref.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004-ref.html
@@ -53,10 +53,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div class="alignStart"><!--normal--></div></div>
     <div class="container"><div class="alignStart"><!--stretch--></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div class="alignStart"><!--baseline--></div></div>
-    <div class="container"><div class="alignEnd"><!--last baseline--></div></div>
-    <br>
     <!-- <self-position>, part 1: -->
     <div class="container"><div class="alignCenter"><!--center--></div></div>
     <div class="container"><div class="alignStart"><!--start--></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004.html b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004.html
index 63c893b6c4f116..070829ba8c6f36 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004.html
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/align3/grid-abspos-staticpos-justify-self-vertWM-004.html
@@ -53,10 +53,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
@@ -79,10 +75,6 @@
     <div class="container"><div style="justify-self: normal"></div></div>
     <div class="container"><div style="justify-self: stretch"></div></div>
     <br>
-    <!-- <baseline-position> -->
-    <div class="container"><div style="justify-self: baseline"></div></div>
-    <div class="container"><div style="justify-self: last baseline"></div></div>
-    <br>
     <!-- <self-position>, part 1 -->
     <div class="container"><div style="justify-self: center"></div></div>
     <div class="container"><div style="justify-self: start"></div></div>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001-ref.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001-ref.xhtml
index 18d4c584846996..c83f5a03ce2112 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001-ref.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001-ref.xhtml
@@ -138,34 +138,5 @@
       <div class="b" style="margin-top: 30px"><div class="fixedSizeChild"/></div>
       <div class="c" style="margin-top: 30px"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox">
-      <div class="a"/>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox">
-      <div class="a"/>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001a.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001a.xhtml
index c7ef7d6aff53a4..96fc4cd0a44811 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001a.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001a.xhtml
@@ -147,34 +147,5 @@
       <div class="b"><div class="fixedSizeChild"/></div>
       <div class="c"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001b.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001b.xhtml
index 19054382cf1a62..0f2a25426b3a73 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001b.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-horiz-001b.xhtml
@@ -148,34 +148,5 @@
       <div class="b"><div class="fixedSizeChild"/></div>
       <div class="c"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001-ref.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001-ref.xhtml
index 460ccef05c15a3..ab407a42e21e58 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001-ref.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001-ref.xhtml
@@ -141,34 +141,5 @@
       <div class="b" style="margin-left: 30px"><div class="fixedSizeChild"/></div>
       <div class="c" style="margin-left: 30px"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox">
-      <div class="a"/>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox">
-      <div class="a" style="margin-left: 190px"/>
-    </div>
-    <div class="flexbox">
-      <div class="a" style="margin-left: 160px"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox">
-      <div class="a" style="margin-left: 120px"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001a.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001a.xhtml
index ef91d5fb770a6d..e8319cb75381f8 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001a.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001a.xhtml
@@ -147,34 +147,5 @@
       <div class="b"><div class="fixedSizeChild"/></div>
       <div class="c"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001b.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001b.xhtml
index 9b9b2fa726a15f..a2e7ae6fb8adc2 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001b.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-content-vert-001b.xhtml
@@ -148,34 +148,5 @@
       <div class="b"><div class="fixedSizeChild"/></div>
       <div class="c"/>
     </div>
-
-    <!-- left -->
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: left">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
-    <!-- right -->
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-    </div>
-    <div class="flexbox" style="align-content: right">
-      <div class="a"/>
-      <div class="b"><div class="fixedSizeChild"/></div>
-      <div class="c"/>
-    </div>
-
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-block.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-block.xhtml
index 569312a700407b..365354506f86a1 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-block.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-block.xhtml
@@ -74,14 +74,6 @@
         background: violet;
         align-self: inherit;
       }
-      .left {
-        background: tan;
-        align-self: left;
-      }
-      .right {
-        background: brown;
-        align-self: right;
-      }
     </style>
   </head>
   <body>
@@ -100,8 +92,6 @@
       <div class="unspecified">unspec</div>
       <div class="initial">initial</div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-ref.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-ref.xhtml
index 356ab3d1c59d1b..a95a724811d0bf 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-ref.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-ref.xhtml
@@ -14,7 +14,7 @@
       .flexbox {
         border: 1px dashed blue;
         height: 200px;
-        width: 640px;
+        width: 560px;
         font-size: 10px;
         line-height: 10px;
       }
@@ -58,12 +58,6 @@
       .inherit {
         background: violet;
       }
-      .left {
-        background: tan;
-      }
-      .right {
-        background: brown;
-      }
    </style>
   </head>
   <body>
@@ -92,8 +86,6 @@
       <div class="unspecified" style="margin-top: 95px">unspec</div>
       <div class="initial" style="margin-top: 95px">initial</div>
       <div class="inherit" style="margin-top: 190px">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-table.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-table.xhtml
index 10180adacdf6ae..1785ca8dfc0a8b 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-table.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-horiz-001-table.xhtml
@@ -76,14 +76,6 @@
         background: violet;
         align-self: inherit;
       }
-      .left {
-        background: tan;
-        align-self: left;
-      }
-      .right {
-        background: brown;
-        align-self: right;
-      }
    </style>
   </head>
   <body>
@@ -102,8 +94,6 @@
       <div class="unspecified">unspec</div>
       <div class="initial">initial</div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001-ref.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001-ref.xhtml
index 1d19034a19eb03..2288c21ace97e0 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001-ref.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001-ref.xhtml
@@ -63,14 +63,6 @@
         background: violet;
         float: right;
       }
-      .left {
-        background: tan;
-        float: left;
-      }
-      .right {
-        background: brown;
-        float: right;
-      }
 
       <!-- We center shrinkwrapped text by putting it into an inline-block, and
            then wrapping that inline-block in a helper-div that has
@@ -108,12 +100,10 @@
         <div class="initial">initial</div>
       </div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
-      <!-- Since the last three divs are floated, the container doesn't include
-           their heights by default. So we add some invisible hacky text (of the
+      <!-- Since the last div is floated, the container doesn't include
+           its height by default. So we add some invisible hacky text (of the
            same font) to make sure our container is tall enough. -->
-      <span style="visibility:hidden">hacky text<br/>(line 2)<br/>(line 3)</span>
+      <span style="visibility:hidden">hacky text</span>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001.xhtml
index e611f48fc38d17..4080d348803329 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-001.xhtml
@@ -69,14 +69,6 @@
         background: violet;
         align-self: inherit;
       }
-      .left {
-        background: tan;
-        align-self: left;
-      }
-      .right {
-        background: brown;
-        align-self: right;
-      }
    </style>
   </head>
   <body>
@@ -95,8 +87,6 @@
       <div class="unspecified">unspec</div>
       <div class="initial">initial</div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001-ref.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001-ref.xhtml
index a9235f07ea35ac..5c2f62abebac7e 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001-ref.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001-ref.xhtml
@@ -66,14 +66,6 @@
         background: violet;
         float: left;
       }
-      .left {
-        background: tan;
-        float: left;
-      }
-      .right {
-        background: brown;
-        float: right;
-      }
 
       <!-- We center shrinkwrapped text by putting it into an inline-block, and
            then wrapping that inline-block in a helper-div that has
@@ -111,12 +103,10 @@
         <div class="initial">initial</div>
       </div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
-      <!-- Since the last three divs are floated, the container doesn't include
-           their heights by default. So we add some invisible hacky text (of the
+      <!-- Since the last div is floated, the container doesn't include
+           its height by default. So we add some invisible hacky text (of the
            same font) to make sure our container is tall enough. -->
-      <span style="visibility:hidden">hacky text<br/>(line 2)<br/>(line 3)</span>
+      <span style="visibility:hidden">hacky text</span>
     </div>
   </body>
 </html>
diff --git a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001.xhtml b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001.xhtml
index d0ef2963c8f814..1016c28f824e86 100644
--- a/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001.xhtml
+++ b/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-align-self-vert-rtl-001.xhtml
@@ -72,14 +72,6 @@
         background: violet;
         align-self: inherit;
       }
-      .left {
-        background: tan;
-        align-self: left;
-      }
-      .right {
-        background: brown;
-        align-self: right;
-      }
    </style>
   </head>
   <body>
@@ -98,8 +90,6 @@
       <div class="unspecified">unspec</div>
       <div class="initial">initial</div>
       <div class="inherit">inherit</div>
-      <div class="left">left</div>
-      <div class="right">right</div>
     </div>
   </body>
 </html>
diff --git a/custom-elements/attribute-changed-callback.html b/custom-elements/attribute-changed-callback.html
index bd467912b99959..5090bfbfbfecdf 100644
--- a/custom-elements/attribute-changed-callback.html
+++ b/custom-elements/attribute-changed-callback.html
@@ -11,6 +11,7 @@
 </head>
 <body>
 <div id="log"></div>
+<parser-created-element title></parser-created-element>
 <script>
 
 var customElement = define_new_custom_element(['title', 'id', 'r']);
@@ -218,6 +219,36 @@
     assert_attribute_log_entry(calls[0], {name: 'title', oldValue: null, newValue: 'hello', namespace: null});
 }, 'attributedChangedCallback must not be enqueued when mutating inline style declaration if the style attribute is not observed');
 
+test(function () {
+    var calls = [];
+    class CustomElement extends HTMLElement { }
+    CustomElement.prototype.attributeChangedCallback = function (...args) {
+        calls.push(create_attribute_changed_callback_log(this, ...args));
+    }
+    CustomElement.observedAttributes = ['title'];
+    customElements.define('parser-created-element', CustomElement);
+    assert_attribute_log_entry(calls[0], {name: 'title', oldValue: null, newValue: '', namespace: null});
+}, 'Upgrading a parser created element must enqueue and invoke attributeChangedCallback for an HTML attribute');
+
+test(function () {
+    var calls = [];
+    class CustomElement extends HTMLElement { }
+    CustomElement.prototype.attributeChangedCallback = function (...args) {
+        calls.push(create_attribute_changed_callback_log(this, ...args));
+    }
+    CustomElement.observedAttributes = ['title'];
+    customElements.define('cloned-element-with-attribute', CustomElement);
+
+    var instance = document.createElement('cloned-element-with-attribute');
+    assert_equals(calls.length, 0);
+    instance.title = '';
+    assert_attribute_log_entry(calls[0], {name: 'title', oldValue: null, newValue: '', namespace: null});
+
+    calls = [];
+    var clone = instance.cloneNode(false);
+    assert_attribute_log_entry(calls[0], {name: 'title', oldValue: null, newValue: '', namespace: null});
+}, 'Upgrading a cloned element must enqueue and invoke attributeChangedCallback for an HTML attribute');
+
 </script>
 </body>
 </html>
diff --git a/custom-elements/parser/parser-sets-attributes-and-children.html b/custom-elements/parser/parser-sets-attributes-and-children.html
index ba331370a78daa..ef4689fac0729e 100644
--- a/custom-elements/parser/parser-sets-attributes-and-children.html
+++ b/custom-elements/parser/parser-sets-attributes-and-children.html
@@ -8,6 +8,7 @@
 <link rel="help" href="https://dom.spec.whatwg.org/#concept-create-element">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
+<script src="../resources/custom-elements-helpers.js"></script>
 </head>
 <body>
 <div id="log"></div>
@@ -15,6 +16,7 @@
 
 var numberOfAttributesInConstructor;
 var numberOfChildNodesInConstructor;
+var attributesChangedCalls = [];
 
 class MyCustomElement extends HTMLElement {
     constructor(...args) {
@@ -22,6 +24,14 @@
         numberOfAttributesInConstructor = this.attributes.length;
         numberOfChildNodesInConstructor = this.childNodes.length;
     }
+
+    attributeChangedCallback(...args) {
+        attributesChangedCalls.push(create_attribute_changed_callback_log(this, ...args));
+    }
+
+    static get observedAttributes() {
+        return ['id', 'class'];
+    }
 };
 customElements.define('my-custom-element', MyCustomElement);
 
@@ -54,6 +64,12 @@
     assert_equals(numberOfChildNodesInConstructor, 0, 'HTML parser must not append child nodes to a custom element before invoking the constructor');
 }, 'HTML parser must set the attributes or append children before calling constructor');
 
+test(function () {
+    assert_equals(attributesChangedCalls.length, 2);
+    assert_attribute_log_entry(attributesChangedCalls[0], {name: 'id', oldValue: null, newValue: 'custom-element-id', namespace: null});
+    assert_attribute_log_entry(attributesChangedCalls[1], {name: 'class', oldValue: null, newValue: 'class1 class2', namespace: null});
+}, 'HTML parser must enqueue attributeChanged reactions');
+
 </script>
 </body>
 </html>
diff --git a/fetch/api/response/response-init-002.html b/fetch/api/response/response-init-002.html
index 0bb2e8d0b3b28d..a48af833644efe 100644
--- a/fetch/api/response/response-init-002.html
+++ b/fetch/api/response/response-init-002.html
@@ -65,6 +65,11 @@
         });
       }, "Testing empty Response Content-Type header");
 
+      test(function() {
+        var response = new Response(null, {status: 204});
+        assert_equals(response.body, null);
+      }, "Testing null Response body");
+
     </script>
   </body>
 </html>
diff --git a/resource-timing/resource_timing.worker.js b/resource-timing/resource_timing.worker.js
new file mode 100644
index 00000000000000..92687f0f7b62b9
--- /dev/null
+++ b/resource-timing/resource_timing.worker.js
@@ -0,0 +1,64 @@
+importScripts("/resources/testharness.js");
+
+function check(initiatorType, protocol) {
+  let entries = performance.getEntries();
+  assert_equals(entries.length, 1);
+
+  assert_true(entries[0] instanceof PerformanceEntry);
+  assert_equals(entries[0].entryType, "resource");
+  assert_true(entries[0].startTime > 0);
+  assert_true(entries[0].duration > 0);
+
+  assert_true(entries[0] instanceof PerformanceResourceTiming);
+  assert_equals(entries[0].initiatorType, initiatorType);
+  assert_equals(entries[0].nextHopProtocol, protocol);
+}
+
+async_test(t => {
+  performance.clearResourceTimings();
+
+  // Fetch
+  fetch("resources/empty.js")
+  .then(r => r.blob())
+  .then(blob => {
+    check("fetch", "http/1.1");
+  })
+
+  // XMLHttpRequest
+  .then(() => {
+    return new Promise(resolve => {
+      performance.clearResourceTimings();
+      let xhr = new XMLHttpRequest();
+      xhr.onload = () => {
+        check("xmlhttprequest", "http/1.1");
+        resolve();
+      };
+      xhr.open("GET", "resources/empty.js");
+      xhr.send();
+    });
+  })
+
+  // Sync XMLHttpREquest
+  .then(() => {
+    performance.clearResourceTimings();
+    let xhr = new XMLHttpRequest();
+    xhr.open("GET", "resources/empty.js", false);
+    xhr.send();
+
+    check("xmlhttprequest", "http/1.1");
+  })
+
+  // ImportScripts
+  .then(() => {
+    performance.clearResourceTimings();
+    importScripts(["resources/empty.js"]);
+    check("other", "http/1.1");
+  })
+
+  // All done.
+  .then(() => {
+    t.done();
+  });
+}, "Performance Resouce Entries in workers");
+
+done();
diff --git a/resource-timing/resources/empty.js b/resource-timing/resources/empty.js
new file mode 100644
index 00000000000000..3b44754e301ded
--- /dev/null
+++ b/resource-timing/resources/empty.js
@@ -0,0 +1 @@
+/* Nothing here */
diff --git a/service-workers/service-worker/local-url-inherit-controller.https.html b/service-workers/service-worker/local-url-inherit-controller.https.html
new file mode 100644
index 00000000000000..e3f0b24f1c94a1
--- /dev/null
+++ b/service-workers/service-worker/local-url-inherit-controller.https.html
@@ -0,0 +1,79 @@
+<!DOCTYPE html>
+<title>Service Worker: local URL windows and workers inherit controller</title>
+<meta name=timeout content=long>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+<script src="resources/test-helpers.sub.js"></script>
+<body>
+<script>
+
+const SCRIPT = 'resources/empty.js';
+const SCOPE = 'resources/local-url-inherit-controller-frame.html';
+
+async function doAsyncTest(t, opts) {
+  let name = opts.scheme + '-' + opts.child;
+  let scope = SCOPE + '?name=' + name;
+  let reg = await service_worker_unregister_and_register(t, SCRIPT, scope);
+  add_completion_callback(_ => reg.unregister());
+  await wait_for_state(t, reg.installing, 'activated');
+
+  let frame = await with_iframe(scope);
+  add_completion_callback(_ => frame.remove());
+  assert_not_equals(frame.contentWindow.navigator.serviceWorker.controller, null,
+                    'frame should be controlled');
+
+  let blobController = await frame.contentWindow.checkChildController(opts);
+
+  let expect = opts.expect === 'inherit'
+             ?  frame.contentWindow.navigator.serviceWorker.controller.scriptURL
+             : null;
+
+  assert_equals(blobController, expect,
+                `${opts.scheme} URL ${opts.child} should ${opts.expect} controller`);
+}
+
+promise_test(function(t) {
+  return doAsyncTest(t, {
+    scheme: 'blob',
+    child: 'iframe',
+    expect: 'inherit',
+  });
+}, 'Same-origin blob URL iframe should inherit service worker controller.');
+
+promise_test(function(t) {
+  return doAsyncTest(t, {
+    scheme: 'blob',
+    child: 'worker',
+    expect: 'inherit',
+  });
+}, 'Same-origin blob URL worker should inherit service worker controller.');
+
+promise_test(function(t) {
+  // Data URLs should result in an opaque origin and should probably not
+  // have access to a cross-origin service worker.  See:
+  //
+  // https://github.com/w3c/ServiceWorker/issues/1262
+  //
+  return doAsyncTest(t, {
+    scheme: 'data',
+    child: 'iframe',
+    expect: 'not inherit',
+  });
+}, 'Data URL iframe should not inherit service worker controller.');
+
+promise_test(function(t) {
+  // Data URLs should result in an opaque origin and should probably not
+  // have access to a cross-origin service worker.  See:
+  //
+  // https://github.com/w3c/ServiceWorker/issues/1262
+  //
+  return doAsyncTest(t, {
+    scheme: 'data',
+    child: 'worker',
+    expect: 'not inherit',
+  });
+}, 'Data URL worker should not inherit service worker controller.');
+
+</script>
+</body>
diff --git a/service-workers/service-worker/resources/local-url-inherit-controller-frame.html b/service-workers/service-worker/resources/local-url-inherit-controller-frame.html
new file mode 100644
index 00000000000000..769c2681c0897b
--- /dev/null
+++ b/service-workers/service-worker/resources/local-url-inherit-controller-frame.html
@@ -0,0 +1,85 @@
+<!DOCTYPE html>
+<html>
+<script>
+
+const frameText =
+`<script>
+  let t = navigator.serviceWorker.controller
+        ? navigator.serviceWorker.controller.scriptURL
+        : null;
+  parent.postMessage(t, "*");
+</` + `script>`;
+
+const workerText =
+`let t = navigator.serviceWorker.controller
+       ? navigator.serviceWorker.controller.scriptURL
+       : null;
+self.postMessage(t);`;
+
+function getChildText(opts) {
+  if (opts.child === 'iframe') {
+    return frameText;
+  }
+
+  if (opts.child === 'worker') {
+    return workerText;
+  }
+
+  throw('unexpected child type ' + opts.child);
+}
+
+function makeURL(opts) {
+  if (opts.scheme === 'blob') {
+    let blob = new Blob([getChildText(opts)]);
+    return URL.createObjectURL(blob);
+  }
+
+  if (opts.scheme === 'data') {
+    let mimetype = opts.child === 'iframe' ? 'text/html'
+                                           : 'text/javascript';
+    return `data:${mimetype},${getChildText(opts)}`;
+  }
+
+  throw(`unexpected URL scheme ${opts.scheme}`);
+}
+
+function testWorkerChild(url) {
+  let w = new Worker(url);
+  return new Promise((resolve, reject) => {
+    w.onmessage = resolve;
+    w.onerror = evt => {
+      reject(evt.message);
+    }
+  });
+}
+
+function testIframeChild(url) {
+  let frame = document.createElement('iframe');
+  frame.src = url;
+  document.body.appendChild(frame);
+
+  return new Promise(resolve => {
+    addEventListener('message', evt => {
+      resolve(evt.data);
+    }, { once: true });
+  });
+}
+
+function testURL(opts, url) {
+  if (opts.child === 'worker') {
+    return testWorkerChild(url);
+  }
+
+  if (opts.child === 'iframe') {
+    return testIframeChild(url);
+  }
+
+  throw(`unexpected child type ${opts.child}`);
+}
+
+function checkChildController(opts) {
+  let url = makeURL(opts);
+  return testURL(opts, url);
+}
+</script>
+</html>
diff --git a/tools/ci/.bashrc b/tools/ci/.bashrc
new file mode 100644
index 00000000000000..bbe03c489aa528
--- /dev/null
+++ b/tools/ci/.bashrc
@@ -0,0 +1,4 @@
+function xvfb_start() {
+    GEOMETRY="$SCREEN_WIDTH""x""$SCREEN_HEIGHT""x""$SCREEN_DEPTH"
+    xvfb-run --server-args="-screen 0 $GEOMETRY -ac +extension RANDR" $@
+}
diff --git a/tools/ci/Dockerfile b/tools/ci/Dockerfile
new file mode 100644
index 00000000000000..28fdd78b3ec008
--- /dev/null
+++ b/tools/ci/Dockerfile
@@ -0,0 +1,76 @@
+FROM ubuntu:16.04
+
+# No interactive frontend during docker build
+ENV DEBIAN_FRONTEND=noninteractive \
+    DEBCONF_NONINTERACTIVE_SEEN=true
+
+# General requirements not in the base image
+RUN apt-get -qqy update \
+  && apt-get -qqy install \
+    bzip2 \
+    ca-certificates \
+    dbus-x11 \
+    git \
+    locales \
+    pulseaudio \
+    python \
+    python-pip \
+    tzdata \
+    sudo \
+    unzip \
+    wget \
+    xvfb
+
+# Installing just the deps of firefox and chrome is moderately tricky, so
+# just install the default versions of them, and some extra deps we happen
+# to know that chrome requires
+
+RUN apt-get -qqy install \
+    firefox \
+    chromium-browser \
+    libnss3-tools \
+    fonts-liberation \
+    indicator-application \
+    libappindicator1 \
+    libappindicator3-1 \
+    libdbusmenu-gtk3-4 \
+    libindicator3-7 \
+    libindicator7
+
+RUN pip install --upgrade pip
+RUN pip install virtualenv
+
+ENV TZ "UTC"
+RUN echo "${TZ}" > /etc/timezone \
+  && dpkg-reconfigure --frontend noninteractive tzdata
+
+RUN useradd test \
+         --shell /bin/bash  \
+         --create-home \
+  && usermod -a -G sudo test \
+  && echo 'ALL ALL = (ALL) NOPASSWD: ALL' >> /etc/sudoers \
+  && echo 'test:secret' | chpasswd
+
+ENV SCREEN_WIDTH 1280
+ENV SCREEN_HEIGHT 1024
+ENV SCREEN_DEPTH 24
+ENV DISPLAY :99.0
+
+USER test
+
+WORKDIR /home/test
+
+COPY .bashrc /home/test/.bashrc
+
+COPY start.sh /home/test/start.sh
+
+# Remove information on how to use sudo on login
+RUN sudo echo ""
+
+RUN git clone --depth=1 https://github.com/w3c/web-platform-tests.git
+
+RUN mkdir -p /home/test/.fonts && \
+    cp web-platform-tests/fonts/Ahem.ttf ~/.fonts && \
+    fc-cache -f -v
+
+RUN mkdir -p /home/test/artifacts
\ No newline at end of file
diff --git a/tools/ci/ci_taskcluster.sh b/tools/ci/ci_taskcluster.sh
new file mode 100755
index 00000000000000..38c84628f15d53
--- /dev/null
+++ b/tools/ci/ci_taskcluster.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if [ $1 == "firefox" ]; then
+    ./wpt run firefox --log-tbpl=- --log-tbpl-level=debug --log-wptreport=../artifacts/wpt_report.json --this-chunk=$3 --total-chunks=$4 --test-type=$2 -y --install-browser --no-pause --no-restart-on-unexpected
+elif [ $1 == "chrome" ]; then
+    ./wpt run chrome --log-tbpl=- --log-tbpl-level=debug --log-wptreport=../artifacts/wpt_report.json --this-chunk=$3 --total-chunks=$4 --test-type=$2 -y  --no-pause --no-restart-on-unexpected
+fi
diff --git a/tools/ci/commands.json b/tools/ci/commands.json
index d682d2a506440c..862fde037b5a3b 100644
--- a/tools/ci/commands.json
+++ b/tools/ci/commands.json
@@ -2,5 +2,7 @@
     "test-jobs": {"path": "jobs.py", "script": "run", "parser": "create_parser", "help": "List test jobs that should run for a set of commits",
                   "virtualenv": false},
     "check-stability": {"path": "check_stability.py", "script": "run", "parser": "get_parser", "parse_known": true, "help": "Check test stability",
-                        "virtualenv": true, "install": ["requests"], "requirements": ["../wptrunner/requirements.txt"]}
+                        "virtualenv": true, "install": ["requests"], "requirements": ["../wptrunner/requirements.txt"]},
+    "generate-tasks": {"path": "taskgraph.py", "script": "run", "parser": "get_parser", "parse_known": true, "help": "Generate taskcluster.yml file containing the run tasks",
+                        "virtualenv": true, "install": ["pyyaml"]}
 }
diff --git a/tools/ci/start.sh b/tools/ci/start.sh
new file mode 100755
index 00000000000000..f4adb90d7cb22e
--- /dev/null
+++ b/tools/ci/start.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+sudo sh -c 'echo "
+127.0.0.1	web-platform.test
+127.0.0.1	www.web-platform.test
+127.0.0.1	www1.web-platform.test
+127.0.0.1	www2.web-platform.test
+127.0.0.1	xn--n8j6ds53lwwkrqhv28a.web-platform.test
+127.0.0.1	xn--lve-6lad.web-platform.test
+0.0.0.0	nonexistent-origin.web-platform.test" >> /etc/hosts'
+
+cd web-platform-tests
+git pull --depth=1
+
+# Install Chome unstable
+deb_archive=google-chrome-unstable_current_amd64.deb
+wget https://dl.google.com/linux/direct/$deb_archive
+
+# Installation will fail in cases where the package has unmet dependencies.
+# When this occurs, attempt to use the system package manager to fetch the
+# required packages and retry.
+if ! sudo dpkg --install $deb_archive; then
+    sudo apt-get -y install --fix-broken
+    sudo dpkg --install $deb_archive
+fi
+
+sudo Xvfb $DISPLAY -screen 0 ${SCREEN_WIDTH}x${SCREEN_HEIGHT}x${SCREEN_DEPTH} &
diff --git a/tools/ci/taskgraph.py b/tools/ci/taskgraph.py
new file mode 100644
index 00000000000000..523bf286433abf
--- /dev/null
+++ b/tools/ci/taskgraph.py
@@ -0,0 +1,119 @@
+import argparse
+import copy
+import os
+
+import yaml
+
+
+here = os.path.dirname(__file__)
+wpt_root = os.path.abspath(os.path.join(here, os.pardir, os.pardir))
+
+
+task_template = {
+    "provisionerId": "{{ taskcluster.docker.provisionerId }}",
+    "workerType": "{{ taskcluster.docker.workerType }}",
+    "extra": {
+        "github": {
+            "events": ["push"],
+            "branches": ["master"],
+        },
+    },
+    "payload": {
+        "maxRunTime": 5400,
+        "image": "harjgam/web-platform-tests:0.5",
+        "command":[
+            "/bin/bash",
+            "--login",
+            "-c",
+            """>-
+            ~/start.sh &&
+            cd /home/test/web-platform-tests &&
+            git fetch {{event.head.repo.url}} &&
+            git config advice.detachedHead false &&
+            git checkout {{event.head.sha}} &&
+            %(command)s"""],
+        "artifacts": {
+            "public/results": {
+                "path": "/home/test/artifacts",
+                "type": "directory"
+            }
+        }
+    },
+    "metadata": {
+        "name": "wpt-%(browser_name)s-%(suite)s-%(chunk)s",
+        "description": "",
+        "owner": "{{ event.head.user.email }}",
+        "source": "{{ event.head.repo.url }}",
+    }
+}
+
+
+file_template = {
+    "version": 0,
+    "tasks": [],
+    "allowPullRequests": "collaborators"
+}
+
+suites = {
+    "testharness": {"chunks": 12},
+    "reftest": {"chunks": 6},
+    "wdspec": {"chunks": 1}
+}
+
+browsers = {
+    "firefox": {"name": "firefox-nightly"},
+    "chrome": {"name": "chrome-dev"}
+}
+
+
+def get_parser():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--dest",
+                        action="store",
+                        default=wpt_root,
+                        help="Directory to write the .taskcluster.yml file to")
+    return parser
+
+
+def fill(template, data):
+    rv = {}
+    for key, value in template.iteritems():
+        rv[key] = fill_inner(value, data)
+    return rv
+
+
+def fill_inner(value, data):
+    if isinstance(value, (str, unicode)):
+        return value % data
+    elif isinstance(value, dict):
+        return fill(value, data)
+    elif isinstance(value, list):
+        return [fill_inner(item, data) for item in value]
+    elif isinstance(value, (float, int, long)):
+        return value
+    else:
+        raise ValueError
+
+
+def run(venv, *args, **kwargs):
+    if not os.path.isdir(kwargs["dest"]):
+        raise ValueError("Invalid directory %s" % kwargs["dest"])
+
+    task_config = copy.deepcopy(file_template)
+    for browser, browser_props in browsers.iteritems():
+        for suite, suite_props in suites.iteritems():
+            total_chunks = suite_props.get("chunks", 1)
+            for chunk in xrange(1, total_chunks + 1):
+                data = {
+                    "suite": suite,
+                    "chunk": chunk,
+                    "browser_name": browser_props["name"],
+                    "command": ("./tools/ci/ci_taskcluster.sh %s %s %s %s" %
+                                (browser, suite, chunk, total_chunks))
+                }
+
+                task_data = fill(task_template, data)
+                task_config["tasks"].append(task_data)
+
+    with open(os.path.join(kwargs["dest"], ".taskcluster.yml"), "w") as f:
+        yaml.dump(task_config, f)
diff --git a/tools/wpt/run.py b/tools/wpt/run.py
index d1e3e49519c914..c6f3dbc0d240e4 100644
--- a/tools/wpt/run.py
+++ b/tools/wpt/run.py
@@ -397,7 +397,8 @@ def log(x):
 
 def run_single(venv, **kwargs):
     from wptrunner import wptrunner
-    return wptrunner.start(**kwargs)
+    wptrunner.start(**kwargs)
+    return
 
 
 def main():
diff --git a/tools/wpt/utils.py b/tools/wpt/utils.py
index e1f4cd4bb5c75d..40e1a45d28d0e5 100644
--- a/tools/wpt/utils.py
+++ b/tools/wpt/utils.py
@@ -39,7 +39,7 @@ def call(*args):
 
     Returns a bytestring of the subprocess output if no error.
     """
-    logger.debug("%s" % " ".join(args))
+    logger.info("%s" % " ".join(args))
     try:
         return subprocess.check_output(args)
     except subprocess.CalledProcessError as e:
diff --git a/tools/wpt/virtualenv.py b/tools/wpt/virtualenv.py
index 8f36aa93585ffd..6abaec5f875811 100644
--- a/tools/wpt/virtualenv.py
+++ b/tools/wpt/virtualenv.py
@@ -7,6 +7,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 class Virtualenv(object):
     def __init__(self, path):
         self.path = path
@@ -21,7 +22,7 @@ def exists(self):
     def create(self):
         if os.path.exists(self.path):
             shutil.rmtree(self.path)
-        call(self.virtualenv, self.path)
+        call(self.virtualenv, self.path, "-p", sys.executable)
 
     @property
     def bin_path(self):
@@ -38,7 +39,14 @@ def pip_path(self):
 
     def activate(self):
         path = os.path.join(self.bin_path, "activate_this.py")
+        logger.info("Activating virtualenv %s" % path)
+        old_sys_path = sys.path[:]
+        logger.info(sys.path)
         execfile(path, {"__file__": path})
+        logger.info(sys.path)
+        for item in sys.path:
+            if item not in old_sys_path:
+                logger.info(item)
 
     def start(self):
         if not self.exists:
@@ -46,7 +54,7 @@ def start(self):
         self.activate()
 
     def install(self, *requirements):
-        call(self.pip_path, "install", *requirements)
+        logger.info(call(self.pip_path, "install", *requirements))
 
     def install_requirements(self, requirements_path):
-        call(self.pip_path, "install", "-r", requirements_path)
+        logger.info(call(self.pip_path, "install", "-r", requirements_path))
diff --git a/tools/wpt/wpt.py b/tools/wpt/wpt.py
index 49f463d2a9ed1e..e183bef230da97 100644
--- a/tools/wpt/wpt.py
+++ b/tools/wpt/wpt.py
@@ -90,7 +90,7 @@ def setup_virtualenv(path, props):
 
 
 def main(prog=None, argv=None):
-    logging.basicConfig(level=logging.INFO)
+    logging.basicConfig(level=logging.DEBUG)
 
     if prog is None:
         prog = sys.argv[0]
diff --git a/web-animations/README.md b/web-animations/README.md
index 475f58a57b1283..f6efbf977f95bc 100644
--- a/web-animations/README.md
+++ b/web-animations/README.md
@@ -98,10 +98,19 @@ Guidelines for writing tests
     Remember, even if we do need to make all tests take, say 200s each, text
     editors are very good at search and replace.
 
-*   Use the `assert_times_equal` assertion for comparing calculated times.
-    It tests times are equal using the precision recommended in the spec whilst
-    allowing implementations to override the function to meet their own
-    precision requirements.
+*   Use the `assert_times_equal` assertion for comparing times returned from
+    the API. This asserts that the time values are equal using a tolerance
+    based on the precision recommended in the spec. This tolerance is applied
+    to *both* of the values being compared. That is, it effectively allows
+    double the epsilon that is used when comparing with an absolute value.
+
+    For comparing a time value returned from the API to an absolute value, use
+    `assert_time_equals_literal`. This tests that the actual value is equal to
+    the expected value within the precision recommended in the spec.
+
+    Both `assert_times_equal` and `assert_time_equals_literal` are defined in a
+    way that implementations can override them to meet their own precision
+    requirements.
 
 *   There are quite a few bad tests in the repository. We're learning as
     we go. Don't just copy them blindly&mdash;please fix them!
diff --git a/web-animations/animation-model/animation-types/property-list.js b/web-animations/animation-model/animation-types/property-list.js
index 1220b455b18ca9..4b917957f7f237 100644
--- a/web-animations/animation-model/animation-types/property-list.js
+++ b/web-animations/animation-model/animation-types/property-list.js
@@ -751,19 +751,19 @@ const gCSSProperties = {
   'justify-content': {
     // https://drafts.csswg.org/css-align/#propdef-justify-content
     types: [
-      { type: 'discrete', options: [ [ 'baseline', 'last baseline' ] ] }
+      { type: 'discrete', options: [ [ 'start', 'end' ] ] }
     ]
   },
   'justify-items': {
     // https://drafts.csswg.org/css-align/#propdef-justify-items
     types: [
-      { type: 'discrete', options: [ [ 'baseline', 'last baseline' ] ] }
+      { type: 'discrete', options: [ [ 'start', 'end' ] ] }
     ]
   },
   'justify-self': {
     // https://drafts.csswg.org/css-align/#propdef-justify-self
     types: [
-      { type: 'discrete', options: [ [ 'baseline', 'last baseline' ] ] }
+      { type: 'discrete', options: [ [ 'start', 'end' ] ] }
     ]
   },
   'left': {
diff --git a/web-animations/interfaces/Animation/playbackRate.html b/web-animations/interfaces/Animation/playbackRate.html
index 9a3b76240f0272..be5bf969498ceb 100644
--- a/web-animations/interfaces/Animation/playbackRate.html
+++ b/web-animations/interfaces/Animation/playbackRate.html
@@ -14,16 +14,14 @@
                              previousAnimationCurrentTime,
                              previousTimelineCurrentTime,
                              description) {
-  const accuracy = 0.001; /* accuracy of DOMHighResTimeStamp */
   const animationCurrentTimeDifference =
     animation.currentTime - previousAnimationCurrentTime;
   const timelineCurrentTimeDifference =
     animation.timeline.currentTime - previousTimelineCurrentTime;
 
-  assert_approx_equals(animationCurrentTimeDifference,
-                       timelineCurrentTimeDifference * animation.playbackRate,
-                       accuracy,
-                       description);
+  assert_times_equal(animationCurrentTimeDifference,
+                     timelineCurrentTimeDifference * animation.playbackRate,
+                     description);
 }
 
 promise_test(t => {
diff --git a/web-animations/interfaces/AnimationEffectTiming/direction.html b/web-animations/interfaces/AnimationEffectTiming/direction.html
index 7bc315da967162..3238f5d7a5e842 100644
--- a/web-animations/interfaces/AnimationEffectTiming/direction.html
+++ b/web-animations/interfaces/AnimationEffectTiming/direction.html
@@ -31,13 +31,13 @@
   const div = createDiv(t);
   const anim = div.animate(null, { duration: 10000, direction: 'normal' });
   anim.currentTime = 7000;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.7,
-                     'progress before updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.7,
+                             'progress before updating direction');
 
   anim.effect.timing.direction = 'reverse';
 
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3,
-                     'progress after updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3,
+                             'progress after updating direction');
 }, 'Can be changed from \'normal\' to \'reverse\' while in progress');
 
 test(t => {
@@ -78,13 +78,13 @@
                              duration: 10000,
                              direction: 'normal' });
   anim.currentTime = 17000;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.7,
-                     'progress before updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.7,
+                             'progress before updating direction');
 
   anim.effect.timing.direction = 'alternate';
 
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3,
-                     'progress after updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3,
+                             'progress after updating direction');
 }, 'Can be changed from \'normal\' to \'alternate\' while in progress');
 
 test(t => {
@@ -94,13 +94,13 @@
                              duration: 10000,
                              direction: 'alternate' });
   anim.currentTime = 17000;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3,
-                     'progress before updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3,
+                             'progress before updating direction');
 
   anim.effect.timing.direction = 'alternate-reverse';
 
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.7,
-                     'progress after updating direction');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.7,
+                             'progress after updating direction');
 }, 'Can be changed from \'alternate\' to \'alternate-reverse\' while in'
    + ' progress');
 
diff --git a/web-animations/interfaces/AnimationEffectTiming/duration.html b/web-animations/interfaces/AnimationEffectTiming/duration.html
index 9caa0e36e05d03..42913f552dd40b 100644
--- a/web-animations/interfaces/AnimationEffectTiming/duration.html
+++ b/web-animations/interfaces/AnimationEffectTiming/duration.html
@@ -19,10 +19,10 @@
   const div = createDiv(t);
   const anim = div.animate({ opacity: [ 0, 1 ] }, 2000);
   anim.effect.timing.duration = 123.45;
-  assert_times_equal(anim.effect.timing.duration, 123.45,
-                     'set duration 123.45');
-  assert_times_equal(anim.effect.getComputedTiming().duration, 123.45,
-                     'getComputedTiming() after set duration 123.45');
+  assert_time_equals_literal(anim.effect.timing.duration, 123.45,
+                             'set duration 123.45');
+  assert_time_equals_literal(anim.effect.getComputedTiming().duration, 123.45,
+                             'getComputedTiming() after set duration 123.45');
 }, 'Can be set to a double value');
 
 test(t => {
@@ -176,8 +176,8 @@
   assert_equals(anim.effect.getComputedTiming().progress, 1,
                 'progress when animation is finished');
   anim.effect.timing.duration *= 2;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5,
-                     'progress after doubling the duration');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5,
+                             'progress after doubling the duration');
   anim.effect.timing.duration = 0;
   assert_equals(anim.effect.getComputedTiming().progress, 1,
                 'progress after setting duration to zero');
diff --git a/web-animations/interfaces/AnimationEffectTiming/endDelay.html b/web-animations/interfaces/AnimationEffectTiming/endDelay.html
index b6793edaed5b1b..3062c8c1565d4d 100644
--- a/web-animations/interfaces/AnimationEffectTiming/endDelay.html
+++ b/web-animations/interfaces/AnimationEffectTiming/endDelay.html
@@ -19,10 +19,10 @@
   const div = createDiv(t);
   const anim = div.animate({ opacity: [ 0, 1 ] }, 2000);
   anim.effect.timing.endDelay = 123.45;
-  assert_times_equal(anim.effect.timing.endDelay, 123.45,
-                     'set endDelay 123.45');
-  assert_times_equal(anim.effect.getComputedTiming().endDelay, 123.45,
-                     'getComputedTiming() after set endDelay 123.45');
+  assert_time_equals_literal(anim.effect.timing.endDelay, 123.45,
+                             'set endDelay 123.45');
+  assert_time_equals_literal(anim.effect.getComputedTiming().endDelay, 123.45,
+                             'getComputedTiming() after set endDelay 123.45');
 }, 'Can be set to a positive number');
 
 test(t => {
diff --git a/web-animations/interfaces/AnimationEffectTiming/iterationStart.html b/web-animations/interfaces/AnimationEffectTiming/iterationStart.html
index 5521f1e85940b9..73bc4810da1958 100644
--- a/web-animations/interfaces/AnimationEffectTiming/iterationStart.html
+++ b/web-animations/interfaces/AnimationEffectTiming/iterationStart.html
@@ -24,7 +24,7 @@
                              duration: 100,
                              delay: 1 });
   anim.effect.timing.iterationStart = 2.5;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
   assert_equals(anim.effect.getComputedTiming().currentIteration, 2);
 }, 'Changing the value updates computed timing when backwards-filling');
 
@@ -37,7 +37,7 @@
                              duration: 100,
                              delay: 0 });
   anim.effect.timing.iterationStart = 2.5;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
   assert_equals(anim.effect.getComputedTiming().currentIteration, 2);
 }, 'Changing the value updates computed timing during the active phase');
 
@@ -51,7 +51,7 @@
                              delay: 0 });
   anim.finish();
   anim.effect.timing.iterationStart = 2.5;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
   assert_equals(anim.effect.getComputedTiming().currentIteration, 3);
 }, 'Changing the value updates computed timing when forwards-filling');
 
diff --git a/web-animations/interfaces/AnimationEffectTiming/iterations.html b/web-animations/interfaces/AnimationEffectTiming/iterations.html
index 32390626463516..3bfaf8e9920d18 100644
--- a/web-animations/interfaces/AnimationEffectTiming/iterations.html
+++ b/web-animations/interfaces/AnimationEffectTiming/iterations.html
@@ -70,10 +70,12 @@
 
   anim.effect.timing.iterations = 2;
 
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0,
-                     'progress after adding an iteration');
-  assert_times_equal(anim.effect.getComputedTiming().currentIteration, 1,
-                     'current iteration after adding an iteration');
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress,
+                             0,
+                             'progress after adding an iteration');
+  assert_time_equals_literal(anim.effect.getComputedTiming().currentIteration,
+                             1,
+                             'current iteration after adding an iteration');
 
   anim.effect.timing.iterations = 0;
 
diff --git a/web-animations/testcommon.js b/web-animations/testcommon.js
index 51b84dd3e534ea..be3827fd5d8e54 100644
--- a/web-animations/testcommon.js
+++ b/web-animations/testcommon.js
@@ -21,10 +21,18 @@ const TIME_PRECISION = 0.0005; // ms
 // times based on their precision requirements.
 if (!window.assert_times_equal) {
   window.assert_times_equal = (actual, expected, description) => {
-    assert_approx_equals(actual, expected, TIME_PRECISION, description);
+    assert_approx_equals(actual, expected, TIME_PRECISION * 2, description);
   };
 }
 
+// Allow implementations to substitute an alternative method for comparing
+// a time value based on its precision requirements with a fixed value.
+if (!window.assert_time_equals_literal) {
+  window.assert_time_equals_literal = (actual, expected, description) => {
+    assert_approx_equals(actual, expected, TIME_PRECISION, description);
+  }
+}
+
 // creates div element, appends it to the document body and
 // removes the created element during test cleanup
 function createDiv(test, doc) {
diff --git a/web-animations/timing-model/animation-effects/active-time.html b/web-animations/timing-model/animation-effects/active-time.html
index 3e3b528d534b10..a2feb2323c3308 100644
--- a/web-animations/timing-model/animation-effects/active-time.html
+++ b/web-animations/timing-model/animation-effects/active-time.html
@@ -25,19 +25,19 @@
 test(t => {
   const anim = createDiv(t).animate(null, 1000);
   anim.currentTime = 500;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
 }, 'Active time in active phase and no start delay is the local time');
 
 test(t => {
   const anim = createDiv(t).animate(null, { duration: 1000, delay: 500 });
   anim.currentTime = 1000;
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
 }, 'Active time in active phase and positive start delay is the local time'
    + ' minus the start delay');
 
 test(t => {
   const anim = createDiv(t).animate(null, { duration: 1000, delay: -500 });
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
 }, 'Active time in active phase and negative start delay is the local time'
    + ' minus the start delay');
 
@@ -58,7 +58,7 @@
                                             fill: 'forwards' });
   anim.finish();
   assert_equals(anim.effect.getComputedTiming().currentIteration, 2);
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3);
 }, 'Active time in after phase with forwards fill is the active duration');
 
 test(t => {
@@ -79,7 +79,7 @@
                                             fill: 'forwards' });
   anim.finish();
   assert_equals(anim.effect.getComputedTiming().currentIteration, 2);
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3);
 }, 'Active time in after phase with forwards fill and positive end delay'
    + ' is the active duration');
 
@@ -91,7 +91,7 @@
                                             fill: 'forwards' });
   anim.finish();
   assert_equals(anim.effect.getComputedTiming().currentIteration, 1);
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.5);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.5);
 }, 'Active time in after phase with forwards fill and negative end delay'
    + ' is the active duration + end delay');
 
@@ -127,7 +127,7 @@
                                             fill: 'both' });
   anim.finish();
   assert_equals(anim.effect.getComputedTiming().currentIteration, 2);
-  assert_times_equal(anim.effect.getComputedTiming().progress, 0.3);
+  assert_time_equals_literal(anim.effect.getComputedTiming().progress, 0.3);
 }, 'Active time in after phase with \'both\' fill is the active duration');
 
 test(t => {
diff --git a/web-animations/timing-model/animations/current-time.html b/web-animations/timing-model/animations/current-time.html
index d2f5075d1b25fa..08f90d9f0c1cbd 100644
--- a/web-animations/timing-model/animations/current-time.html
+++ b/web-animations/timing-model/animations/current-time.html
@@ -68,7 +68,7 @@
 
   return animation.ready.then(() => waitForAnimationFrames(1))
   .then(() => {
-    assert_times_equal(animation.currentTime, 0);
+    assert_time_equals_literal(animation.currentTime, 0);
   });
 }, 'The current time does not progress if playback rate is 0');
 
diff --git a/web-animations/timing-model/animations/playing-an-animation.html b/web-animations/timing-model/animations/playing-an-animation.html
index 2beed475e7ec41..1064192051442e 100644
--- a/web-animations/timing-model/animations/playing-an-animation.html
+++ b/web-animations/timing-model/animations/playing-an-animation.html
@@ -14,26 +14,26 @@
 test(t => {
   const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
   animation.currentTime = 1 * MS_PER_SEC;
-  assert_times_equal(animation.currentTime, 1 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 1 * MS_PER_SEC);
   animation.play();
-  assert_times_equal(animation.currentTime, 1 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 1 * MS_PER_SEC);
 }, 'Playing a running animation leaves the current time unchanged');
 
 test(t => {
   const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
   animation.finish();
-  assert_times_equal(animation.currentTime, 100 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 100 * MS_PER_SEC);
   animation.play();
-  assert_times_equal(animation.currentTime, 0);
+  assert_time_equals_literal(animation.currentTime, 0);
 }, 'Playing a finished animation seeks back to the start');
 
 test(t => {
   const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
   animation.playbackRate = -1;
   animation.currentTime = 0;
-  assert_times_equal(animation.currentTime, 0);
+  assert_time_equals_literal(animation.currentTime, 0);
   animation.play();
-  assert_times_equal(animation.currentTime, 100 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 100 * MS_PER_SEC);
 }, 'Playing a finished and reversed animation seeks to end');
 
 test(t => {
diff --git a/web-animations/timing-model/animations/set-the-animation-start-time.html b/web-animations/timing-model/animations/set-the-animation-start-time.html
index 1526be05766edb..d2a311d4dd4019 100644
--- a/web-animations/timing-model/animations/set-the-animation-start-time.html
+++ b/web-animations/timing-model/animations/set-the-animation-start-time.html
@@ -80,9 +80,9 @@
 
   // If we set the start time, however, we should clear the hold time.
   animation.startTime = document.timeline.currentTime - 2000;
-  assert_times_equal(animation.currentTime, 2000,
-                     'The current time is calculated from the start time,'
-                     + ' not the hold time');
+  assert_time_equals_literal(animation.currentTime, 2000,
+                             'The current time is calculated from the start'
+                             + ' time, not the hold time');
 
   // Sanity check
   assert_equals(animation.playState, 'running',
@@ -99,13 +99,14 @@
   // are resolved).
   animation.startTime = document.timeline.currentTime - 1000;
   assert_equals(animation.playState, 'running');
-  assert_times_equal(animation.currentTime, 1000,
-                     'Current time is resolved for a running animation')
+  assert_time_equals_literal(animation.currentTime, 1000,
+                             'Current time is resolved for a running animation');
 
   // Clear start time
   animation.startTime = null;
-  assert_times_equal(animation.currentTime, 1000,
-                     'Hold time is set after start time is made unresolved');
+  assert_time_equals_literal(animation.currentTime, 1000,
+                             'Hold time is set after start time is made'
+                             + ' unresolved');
   assert_equals(animation.playState, 'paused',
                 'Animation reports it is paused after setting an unresolved'
                 + ' start time');
diff --git a/web-animations/timing-model/animations/set-the-timeline-of-an-animation.html b/web-animations/timing-model/animations/set-the-timeline-of-an-animation.html
index 8a4421309b9eda..24f201d550c469 100644
--- a/web-animations/timing-model/animations/set-the-timeline-of-an-animation.html
+++ b/web-animations/timing-model/animations/set-the-timeline-of-an-animation.html
@@ -26,7 +26,7 @@
   animation.timeline = document.timeline;
 
   assert_equals(animation.playState, 'paused');
-  assert_times_equal(animation.currentTime, 50 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 50 * MS_PER_SEC);
 }, 'After setting timeline on paused animation it is still paused');
 
 test(t => {
@@ -39,7 +39,7 @@
   animation.timeline = document.timeline;
 
   assert_equals(animation.playState, 'paused');
-  assert_times_equal(animation.currentTime, 200 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 200 * MS_PER_SEC);
 }, 'After setting timeline on animation paused outside active interval'
    + ' it is still paused');
 
@@ -141,7 +141,7 @@
 
   assert_false(animation.pending);
   assert_equals(animation.playState, 'paused');
-  assert_times_equal(animation.currentTime, 50 * MS_PER_SEC);
+  assert_time_equals_literal(animation.currentTime, 50 * MS_PER_SEC);
 }, 'After clearing timeline on paused animation it is still paused');
 
 test(t => {