Fix contributed by matavenrath@nvidia.com.

This fixes BindingsBenchmark::drawBenchmark to take only 3% instead of
15% of the time spent in
BindingsBenchmark.Run/gl_100_objects_allocated_at_initialization.

Bug: angleproject:2777
Change-Id: I5b5b6f167289b947767b40e7761d90cf06c49816
Reviewed-on: https://chromium-review.googlesource.com/1181868Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>