This makes testing with random gc stress use the status file entrees
for gc fuzzing as well, since many test cases not suitable for one, are
not suitable for the other.

This also skips two more tests that rely on assert(Un)Optimized, which
is unreliable with gc fuzzing.

TBR=sigurds@chromium.org

Change-Id: I33a617b251d5cf65cf6e486d07ec55cde050b8ab
Reviewed-on: https://chromium-review.googlesource.com/1021082
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52701}