Previously, Atomics.notify was just an alias to Atomics.wake, which
doesn't quite let us add a use counter for these individual builtins.

This patch refactors the existing Atomics.wake into a separate
function that is called from two separate builtins.

Bug: v8:7883
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: If54c8f769b7949d88d327cfb2f70db394f32a0b7
Reviewed-on: https://chromium-review.googlesource.com/1234581
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Ben Smith <binji@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56105}