[Cocoa] Youtube videos don't always size correctly, both inline and fullscreen
<rdar://problem/106974872>
Pull request: https://github.com/WebKit/WebKit/pull/13066
Committed 263292@main (8addb776de1b): <https://commits.webkit.org/263292@main> Reviewed commits have been landed. Closing PR #13066 and removing active labels.