[iOS] Non-fullscreen content peeks into top safe area in element fullscreen mode
<rdar://problem/118147164>
Pull request: https://github.com/WebKit/WebKit/pull/20205
Committed 270424@main (e5bf2b80f8e5): <https://commits.webkit.org/270424@main> Reviewed commits have been landed. Closing PR #20205 and removing active labels.