Use a similar gesture to close the current tab.

[mralexgray]

Love the tweak. Add this and I'll be in (tab) hog heaven! I'll help, where do I start?

[stonesam92]

Yeah, I'm thinking of adding "swipe up to close".

If you want to do it yourself, you can just watch the y translation of the gesture recognizer in [BrowserController didPan:]. I don't know for sure, but presumably there will be some "close active tab" method on TabController you can call to close the current tab.

If not I'll get round to it in a couple days.