Created attachment 229736 [details]
Attached testcase (fix it to point to a local copy of ducky.png) shows a bug where the body background is only partially painted. It flashes horribly when hovering the boxes.
This is a blocker to Safari shipping blend modes.
Created attachment 229781 [details]
even simpler version. This has to be a recent break since basic content is now drawing incorrectly.
It looks like this was caused by https://bugs.webkit.org/show_bug.cgi?id=130892
(In reply to comment #3)
> It looks like this was caused by https://bugs.webkit.org/show_bug.cgi?id=130892
Nope, it's https://bugs.webkit.org/show_bug.cgi?id=129154.
I'm looking into it.
Created attachment 230143 [details]
The patch I attached avoids creating a transparency layer for the root renderer that has unisolated blending descendants. However, the issue with background being painted incompletely is not fixed for other reasons that trigger transparency layers on the document element: opacity, mask or mix-blend-mode. This issue is reported here: https://bugs.webkit.org/show_bug.cgi?id=75460.
Comment on attachment 230143 [details]
Clearing flags on attachment: 230143
Committed r167796: <http://trac.webkit.org/changeset/167796>
All reviewed patches have been landed. Closing bug.