Defence in depth patch to prevent JavaScript from executing
from within IterateElements.

R=ishell@chromium.org
R=cbruni@chromium.org

Bug: chromium:1195977
Change-Id: Ie59d468b73b94818cea986a3ded0804f6dddd10b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2819941Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73898}