Created attachment 365350 [details] Testcase position:absolute inside overflow which is stacking context jiggles when scrolled.
<rdar://problem/49065322>
The compositing layer for the overflow:scroll is missing the "has composited descendant" bit.
Created attachment 365441 [details] Patch
Comment on attachment 365441 [details] Patch Clearing flags on attachment: 365441 Committed r243309: <https://trac.webkit.org/changeset/243309>
All reviewed patches have been landed. Closing bug.