The test deliberately tries to render a scene using an invalid texture.
ANGLE rendered this correctly, but when it bound the dummy 1x1 black texture
that's used instead of invalid textures, it didn't bind a sampler state. This meant
that D3D had no pixel shader samplers bound, and outputted a debug warning.

Also, technically the test should have been setting GL_UNPACK_ALIGNMENT=1,
but that wasn't impacting the result of the test.

BUG=angleproject:1248

Change-Id: I871706d518077ea840a585ae0df8f9176e130cb1
Reviewed-on: https://chromium-review.googlesource.com/321391Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>