This microbenchmark targets a variety of blit use cases, including
color blit, depth/stencil blit, and multisample resolve blit.

BUG=angleproject:1710

Change-Id: Ia8b3eb40af29e809e803ed48a69f3975b97fd80b
Reviewed-on: https://chromium-review.googlesource.com/435515Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>