The AtomicWeak wscope was nested within the AtomicMark scope. Both
should be top level scopes and should be nested within each other.

Bug: chromium:1056170
Change-Id: I1d695c1a3a24fff31aa57893739dca4b558901fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883663
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74485}