Sync the tests in web-platform-tests/html/semantics/popovers.
https://github.com/WebKit/WebKit/pull/9800
<rdar://problem/105295635>
Committed 260128@main (0041f5bf29c3): <https://commits.webkit.org/260128@main> Reviewed commits have been landed. Closing PR #9800 and removing active labels.