This is for tracking work to implement changes discussed in https://github.com/w3c/csswg-drafts/issues/5611.
<rdar://problem/76002918>
This seems mostly (only?) tested by css/css-contain/content-visibility/animation-display-lock.html.
Pull request: https://github.com/WebKit/WebKit/pull/17540
Committed 268312@main (37f52f4720ba): <https://commits.webkit.org/268312@main> Reviewed commits have been landed. Closing PR #17540 and removing active labels.