Adds considerable overhead to wall time on Adreno. Not tested on
other platforms.

Bug: angleproject:4879
Change-Id: Ib219f14162fb5768e484f717ed2a870478bd1c86
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2321404Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>