This is part of Cobalt's upstream effort to be more in sync with V8.
Cobalt does not trigger the atomics functions in runtime-atomics.cc so
we use dummy implementations for now.

Bug: v8:10927
Change-Id: I2da75b7f9b22b41a1ff00af1ab4b43641e9a33bf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2963801
Commit-Queue: John Xu <johnx@google.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75317}