[iOS] PiP-then-Fullscreen results in broken controls in fullscreen mode
<rdar://problem/100442052>
Pull request: https://github.com/WebKit/WebKit/pull/6560
Committed 256812@main (82b82f5d1af6): <https://commits.webkit.org/256812@main> Reviewed commits have been landed. Closing PR #6560 and removing active labels.