Functionality added to the WebGPU/WGSL spec after its first shipment in a browser. Loosens a restriction where using readonly depth-stencil attachments in a render pass required both aspects (depth and stencil) to be readonly. This was too strict, and prevent use-cases where for example the depth is used readonly for contact shadow tracing, while the stencil buffer is written to do identify pixels for further processing. (Both Unity and Unreal do things with mixed depth-stencil readonliness).