Suspending the backing store is not necessary anymore since both zoom and scroll adjustments happen in an animation.
Created attachment 176309 [details] Patch
Comment on attachment 176309 [details] Patch LGTM.
Comment on attachment 176309 [details] Patch Clearing flags on attachment: 176309 Committed r135898: <http://trac.webkit.org/changeset/135898>
All reviewed patches have been landed. Closing bug.