400 tests in dEQP-GLES3.functional.texture go from unsupported to passing.

BUG=angleproject:884

Change-Id: I51927dffbc5931c7d1b80e72f55c620197736724
Reviewed-on: https://chromium-review.googlesource.com/298484Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>