... by adding ChangeAlertMechanism enum instead of two bool values and
removing code duplication in tests.

Bug: v8:11074
Change-Id: I90f63bd1c9e858dc3b0a4f190c19f092437257cd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2536458Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71185}