dEQP resetState generates a GL error and exits when trying to reset the
pixel buffers after a test.

BUG=angleproject:1149

Change-Id: I133788c6c2f17074bf5bbf5cd17b63338352765f
Reviewed-on: https://chromium-review.googlesource.com/297081Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>