Created attachment 416639 [details] Testcase In the attached testcase, the sticky element gets pushed out of view as you scroll down and should not. In RenderBoxModelObject::computeStickyPositionConstraints(), containingBlock->layoutOverflowRect() returns a rect that is too short, but only when inside flex layout.
<rdar://problem/70956639>
Created attachment 416648 [details] Patch
Committed r271053: <https://trac.webkit.org/changeset/271053> All reviewed patches have been landed. Closing bug and clearing flags on attachment 416648 [details].