https://webidl.spec.whatwg.org/#LegacyLenientSetter Fullscreen API use this attribute.
Pull request: https://github.com/WebKit/WebKit/pull/8121
<rdar://problem/103805698>
Committed 258940@main (1c2466b7b716): <https://commits.webkit.org/258940@main> Reviewed commits have been landed. Closing PR #8121 and removing active labels.