This method was intended to run single-threaded, so with parallel
marking disabled. While correctness isn't an issue here (simply because
we will later run this method single-threaded as well), some CHECKs do
not hold when parallel marking is active.

Bug: chromium:1325628
Change-Id: Iedebcf6241835011982217b1452271e38a36ce9d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3700074
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81073}