This validation was previously acceptable because all renderers supported all
compressed formats in the format tables.  Adding new formats that are not
universally supported would have caused failures in the dEQP negative API
tests.

BUG=angleproject:1185

Change-Id: I102a3286a351a7c8936527963a382d9673341fc0
Reviewed-on: https://chromium-review.googlesource.com/308490Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>