This is a reland of 9436e8a8

This CL simplifies the wasm/futex.js test so that it doesn't push the
limits of d8.

Original change's description:
> [wasm] Add I64AtomicWait implementation
>
> Bug=v8:8075
> R=adamk@chromium.org,binji@chromium.org
>
> Change-Id: I11ef5daccd043123b23e60c93ee0df79cabe9ccd
> Reviewed-on: https://chromium-review.googlesource.com/c/1342948
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Ben Smith <binji@chromium.org>
> Commit-Queue: Aseem Garg <aseemgarg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#57917}

Change-Id: Ifd26f1ecdb9fe24a1896162bb4d4285f9188a9ba
Reviewed-on: https://chromium-review.googlesource.com/c/1351304
Commit-Queue: Aseem Garg <aseemgarg@chromium.org>
Reviewed-by: Ben Smith <binji@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57953}