There's a lot of heap thrashing below ensureEventAncestors() during event dispatch due to Vectors with zero inline capacity.
Created attachment 179359 [details] Cowboy patch
Comment on attachment 179359 [details] Cowboy patch Clearing flags on attachment: 179359 Committed r137680: <http://trac.webkit.org/changeset/137680>
All reviewed patches have been landed. Closing bug.