By using atomic accessors.

Change-Id: I7ff8660aa118c809da9ce6ff851ebd5080a7b1c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3217197
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77318}