During a final atomic pause CrossThreadPersistent handles need to be
frozen after they have been marked to avoid any
WeakCrossThreadPersistent handles creating new strong references
(through their Lock() call) that would retain objects.

Handles are frozen by acquiring a lock. Since this lock is also taking
by other threads on WCTP::Lock() this can introduce jank.

This CL improves the situation by delaying processing of CTP
references until absolutely necessary, i.e., when we have otherwise no
more objects to mark.

Bug: chromium:1252743
Change-Id: I872f38c6d24d7955bea74fd59685abd3019b385e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3194253Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77139}