Add logic to determine hasUAVisualTransition value for MacOS/iOS.
<rdar://problem/118347060>
Pull request: https://github.com/WebKit/WebKit/pull/20988
Committed 275438@main (44a5e909d5d7): <https://commits.webkit.org/275438@main> Reviewed commits have been landed. Closing PR #20988 and removing active labels.