Should return INVALID_ENUM when uncompressed texture passed to
compressed image constructor.

BUG=angleproject:1168

Change-Id: If30f0407e7455d6e19432831883d33a1e8bfec9a
Reviewed-on: https://chromium-review.googlesource.com/303750Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>