Useful for perf testing/comparison.

Bug: angleproject:4729
Change-Id: Ic46424570dcef0a30d506962f546910ba7440595
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2241620Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>