Such as making the Disallow* scope always the first thing in a function,
and const-ifying a few members.

Bug: v8:7790
Change-Id: I78e0701101ee63475bfa30230a2da54da730ba73
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1679508
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62418}