Keep idiomatic state loop but rely on USE() to avoid
warning about unused variables.

Bug: v8:11687
Change-Id: Icde295723c5d389d827280f70a65776866d4e7a9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2850645
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74200}