http://trac.webkit.org/changeset/150399 made it so scrollbars in overflow areas never paint.
Created attachment 202767 [details]
Thank you! http://trac.webkit.org/changeset/150631
*** Bug 116721 has been marked as a duplicate of this bug. ***
Comment on attachment 202767 [details]
Why no regression test?
We don't have a way to test overlay scrollbar painting.
(In reply to comment #5)
> We don't have a way to test overlay scrollbar painting.
We could mimic the animation suppress for the mock scrollbar theme (to make it not paint at all), but it might be an overstretch.