--stress-marking and --stress-scavenge flags with the value
greater than 0 enable additional tracking, allocation observers etc.

--fuzzer-analysis switches --stress-* flags into analysis mode,
which means that all allocation observers and additional checks
are still executed, but GC is not influenced by them. It also
provides analysis information needed by the fuzzer on the stdout.

Bug: v8:6972
Change-Id: I5ac45adb311441d57d5b951aeec036e689930e9f
Reviewed-on: https://chromium-review.googlesource.com/814536Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michał Majewski <majeski@google.com>
Cr-Commit-Position: refs/heads/master@{#50453}