There's nothing clipping the page during a swipe, so if you're zoomed in, you don't see the edge of the page, just more tiles.
Created attachment 230776 [details]
Comment on attachment 230776 [details]
Clearing flags on attachment: 230776
Committed r168234: <http://trac.webkit.org/changeset/168234>
All reviewed patches have been landed. Closing bug.