This will make --regenerate_expected_files flag work for message tests.

Bug: v8:10773
Change-Id: Ica87bd69bd0a41e2a3c168d2200d0cd0c7f094da
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2842387
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74127}