Pass texture base level to shaders on D3D11 The base level is passed to shaders in an array included in the driver uniform block. This is done on feature levels above 9_3, which treat samplers as indices to sampler arrays in shaders. A separate uniform block couldn't be used for the sampler metadata, since that would bring the number of available uniform blocks down to below minimum level defined by GLES 3.0. BUG=angleproject:596 TEST=angle_end2end_tests Change-Id: Ie040521402f9996d51a978aeeba9222e9dd761ce Reviewed-on: https://chromium-review.googlesource.com/326290 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>