Overlay scrollbars without layers never paint in overflow regions in tiled drawing mode. <rdar://problem/11289546>
Created attachment 141295 [details] Patch
Comment on attachment 141295 [details] Patch Can we land a regression test for this? Manual test if necessary?
We don't have a way to test overlay scrollbars, and we also don't have a way to test tiled drawing. Even the very simplest <div style="overflow:scroll"> will demonstrate the bug (so long as there is enough overflow to require the scrollbar). I definitely could land a manual test like that, but it's so simple that I'm not sure it's valuable. Is it?
http://trac.webkit.org/changeset/116711