This is a reland of e2016cf0. The fix is
in PS2, with a comment why it is needed.

Original change's description:
> [d8] Use predictable platform if --predictable is passed
>
> We currently only use the predictable platform if --verify-predictable
> is passed, which is confusing and not following the comment on the
> --predictable flag ("enable predictable mode").
>
> This CL fixes that and makes --verify-predictable imply --predictable to
> also allow to only pass --verify-predictable.
>
> R=ahaas@chromium.org
> CC=mlippautz@chromium.org
>
> Bug: v8:11879
> Change-Id: Ifb9683ddc4fab374ce519169533c90244175bb48
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3094010
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#76305}

Bug: v8:11879
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_isolates_rel_ng
Change-Id: I7bb7a6af722ee1cc447bc668385543dd72fd309b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097867
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76322}