Per https://html.spec.whatwg.org/multipage/semantics-other.html#selector-valid.
Pull request: https://github.com/WebKit/WebKit/pull/8919
Committed 259422@main (7c77ae894095): <https://commits.webkit.org/259422@main> Reviewed commits have been landed. Closing PR #8919 and removing active labels.
<rdar://problem/104694472>