This CL fixes wrong parentheses that caused the sort-length benchmark
to generate "random" arrays that only contained zeroes.

R=ishell@chromium.org

Change-Id: Ie2a564da037425a4ef9c2417597cdc13b497e32b
Reviewed-on: https://chromium-review.googlesource.com/1186332Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#55336}