With --stress-scavenge it is possible that we don't have a memento for
the object we are interested in anymore, making the test useless.

Bug: v8:11701
Change-Id: I05984de33dc0c21d01023ebaa4ceebacfb63cc84
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2851889
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Auto-Submit: Patrick Thier <pthier@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74218}