The access made unsafe were chosen according what's hot in
JSTests/Regexp and Octane/regexp.

Bug: chromium:932919
Change-Id: I8229370f2dd7d0937e9d561f6957fb9dba6d6a25
Reviewed-on: https://chromium-review.googlesource.com/c/1477270Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59673}