Long term, ideally, these would be fixed and this flag can be removed.
For now, this is an expedient way to allow enabling -Wshadow in
Chromium.

Bug: chromium:794619
Change-Id: I038e5fc758fbb8284bb28cb4f7f8a4c44da0db66
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3173891
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76996}