[Cocoa] Sometimes a YouTube video is incorrectly sized, and doesn't respond to window resize
<rdar://problem/109754524>
Pull request: https://github.com/WebKit/WebKit/pull/14609
Committed 264832@main (ae406cb584f9): <https://commits.webkit.org/264832@main> Reviewed commits have been landed. Closing PR #14609 and removing active labels.