This halfs the test size but also halfs the baseline for the score to
make it comparable.

Bug: v8:7926
Change-Id: Id3769def6a555ef1bddf8dd5e54c04b8652e5b54
Reviewed-on: https://chromium-review.googlesource.com/1188465Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#55403}