- Add an ActiveSuspender root, similar to the ActiveContinuation root.
- Add the missing "parent" field to the Suspender, which points to the
outer Suspender when they are nested, and update that field when
entering a new Suspender.
- Add the missing "state" field and update it when the state of the
Suspender changes.

R=ahaas@chromium.org
CC=​fgm@chromium.org

Bug: v8:12191
Change-Id: I7a95f44f81390a347c6ef252ec6184fb4f0b0455
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3345003Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78582}