Like https://commits.webkit.org/258795@main, use ThreadSafeWeakPtr in this class.
Pull request: https://github.com/WebKit/WebKit/pull/8558
Committed 258845@main (7eb147bf101d): <https://commits.webkit.org/258845@main> Reviewed commits have been landed. Closing PR #8558 and removing active labels.
<rdar://problem/104189342>