We were skipping some validation, which was confusing dEQP. We can
still no-op, but do this after all validation.

BUG=angleproject:901

Change-Id: I9888c1aca851519e9c7da210c983ba6012e95932
Reviewed-on: https://chromium-review.googlesource.com/266926Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>