.. as a custom data structure with questionable value.

Also: a few drive-by refactors.

Change-Id: I74957b70c4357795dc46ef5520d58b6a78be31b2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3240823
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77674}