This CL adds sampling of depth-only and stencil-only texture
views on all backends. However, Metal on macOS <= 10.11 will
need a workaround to use separate depth/stencil textures for
each aspect since it is impossible to sample the stencil
aspect of a combined depth/stencil texture.
Also fixes sampling of depth24plus on D3D12 which had an
incomplete check for determining if a TYPELESS format is
necessary.
Bug: dawn:439, dawn:553
Change-Id: Id4991c565f822add200054296714e2dcd330119a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/30725
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Stephen White <senorblanco@chromium.org>