Use it instead of AffectsNextSibling/AffectedByPreviousSibling bits, similar to ChildrenAffectedByBackwardPositionalRules bit. This is more efficient and requires way less marking.
<rdar://problem/38151470>
<rdar://problem/38151488>
Created attachment 335022 [details] patch
Comment on attachment 335022 [details] patch Clearing flags on attachment: 335022 Committed r229307: <https://trac.webkit.org/changeset/229307>
All reviewed patches have been landed. Closing bug.