Add cases that bindImageTexture binds a single layer of a
two-dimensional array, three-dimensional, or cube map texture.

BUG=angleproject:1987
TEST=angle_end2end_tests.ComputeShaderTest.*

Change-Id: I75883ef05c509100e5164a5add69167a41203101
Reviewed-on: https://chromium-review.googlesource.com/856320
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>