This updates fast path checks in string's search/match/replace/split/matchAll
methods.

Bug: v8:8361
Change-Id: I0377aff21e380d6c718e7471f8964e10c030281b
Reviewed-on: https://chromium-review.googlesource.com/c/1333668
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57509}