We have back swipe, but not forwards. Turns out this is because the gesture recognizer, which is on the WKView, is cancelled when the swipe starts and the WKView is reparented. We should be swiping the scrollview instead, anyway.
Created attachment 223686 [details]
Comment on attachment 223686 [details]
Clearing flags on attachment: 223686
Committed r163795: <http://trac.webkit.org/changeset/163795>
All reviewed patches have been landed. Closing bug.