This is now used by <details> / <summary> so we should no longer gate it behind the popover flag.
<rdar://problem/114500635>
Pull request: https://github.com/WebKit/WebKit/pull/17108
Committed 267331@main (a7a424ab6eb4): <https://commits.webkit.org/267331@main> Reviewed commits have been landed. Closing PR #17108 and removing active labels.