Add fast paths for Element's disconnectFromResizeObservers() & disconnectFromIntersectionObservers().
Pull request: https://github.com/WebKit/WebKit/pull/11391
Committed 261540@main (ac6e95d2d0d3): <https://commits.webkit.org/261540@main> Reviewed commits have been landed. Closing PR #11391 and removing active labels.
<rdar://problem/106585516>