Adds some benchmarks copied from v8:4762.

BUG=v8:4762, v8:5460
R=adamk@chromium.org

Change-Id: I0b96080042781c2c46c0c8a3896a921bde97c1e5
Reviewed-on: https://chromium-review.googlesource.com/475934Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#44629}