As an optimization, RegisterWeakReferenceIfNeeded checks whether the
target object is marked, and only registers it if it's not marked.
The target object may still be under construction, in which case
checking the mark bit will race with allocating the object.

Bug: chromium:1056170, chromium:1232339
Change-Id: I0a41afba7f48f288f708441176f89509a81ebb09
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3048171
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75879}