Collapsing through is handled in BlockFormattingContext::Quirks::stretchedInFlowHeight
Created attachment 360433 [details] Patch
Comment on attachment 360433 [details] Patch Clearing flags on attachment: 360433 Committed r240653: <https://trac.webkit.org/changeset/240653>
All reviewed patches have been landed. Closing bug.
<rdar://problem/47631320>