HasSeenViewportConstrainedAncestor 496 Source/core/rendering/RenderLayer.cpp if ((flags & HasChangedAncestor) || (flags & HasSeenViewportConstrainedAncestor) || (flags & IsOverflowScroll)) HasSeenViewportConstrainedAncestor 500 Source/core/rendering/RenderLayer.cpp flags |= HasSeenViewportConstrainedAncestor;