If the context is in strict mode, then we can avoid iterating the
stack since we cannot go stricter than that.

Bug: chromium:925289
Change-Id: I422176c85f2dfd9176a60bc7c3a7674f96238bd0
Reviewed-on: https://chromium-review.googlesource.com/c/1439396Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59130}