We already generate an INVALID_VALUE in the ValidES3InternalFormat check
above.  If an error is generated here, it is because the internal format
and type are not valid.

TEST: conformance2/textures/misc/tex-image-with-bad-args
BUG=angleproject:1958
BUG=angleproject:1715

Change-Id: I50d479e64d687cc971c8f41b5691dcb123da0391
Reviewed-on: https://chromium-review.googlesource.com/499690Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>