This will allow Node.js to properly track async context in thenables.

Change-Id: If441423789a78307a57ad7e645daabf551cddb57
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2215624Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Gus Caplan <me@gus.host>
Cr-Commit-Position: refs/heads/master@{#68207}