https://drafts.csswg.org/css-contain-3/#container-shorthand
Created attachment 449936 [details] Patch
Created attachment 449946 [details] Patch for landing
Committed r288576 (246399@main): <https://commits.webkit.org/246399@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 449946 [details].
<rdar://problem/88039067>