dEQP tries to test specific GL ES errors, but also triggers errors in
the additional WebGL validation. This commit reoders ANGLE's validation so
that WebGL-specific validation for draws is done after the common GL ES
checks.

BUG=angleproject:2021

Change-Id: Ie06b132ef6a4378f7c82ae8d354a8343d897c478
Reviewed-on: https://chromium-review.googlesource.com/493828
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>