It's like WeakPtr, but thread safe!
<rdar://problem/102483501>
Pull request: https://github.com/WebKit/WebKit/pull/6602
*** This bug has been marked as a duplicate of bug 238871 ***
Committed 256848@main (4b51a0df4d5c): <https://commits.webkit.org/256848@main> Reviewed commits have been landed. Closing PR #6602 and removing active labels.