TurboFan reads the value in HeapNumber, and TSAN detects a data
race between this read and sets on the main thread elsewhere.
We mark this as relaxed atomic (meaning, correct value of the read
is not guaranteed). The compiler uses the dependency mechanism
to re-read the value safely on the main thread later, and aborts
compilation if a change is detected.

Bug: chromium:1224277, v8:7790
Change-Id: I8931d8989812550c0c57b6bd27aa796f6f5e779d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2996201Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75586}