[Gecko Bug 1429384] Stop toggling selectedness state of <option disabled>. r=automatedtester#120

jgraham wants to merge 22 commits into

masterjgraham/web-platform-tests:masterfrom

gecko/sync/upstream/open/1429384/1jgraham/web-platform-tests:gecko/sync/upstream/open/1429384/1Copy head branch name to clipboard