Allow `UUID`-backed `ObjectIdentifier`s to be created.
<rdar://problem/128772989>
Pull request: https://github.com/WebKit/WebKit/pull/29134
Committed 279402@main (3e6c9b9adb42): <https://commits.webkit.org/279402@main> Reviewed commits have been landed. Closing PR #29134 and removing active labels.