ReadonlybindingBinding number, matching the shader's @binding.
Optional ReadonlybufferBuffer binding shape — group 0's uniform block.
Optional ReadonlysamplerSampler binding shape — group 1's mapSampler (§77).
Optional ReadonlytextureSampled-texture binding shape — group 1's map (§77).
ReadonlyvisibilityBit set from GPU_SHADER_STAGE.
One entry of a bind-group layout — see
wgpu-bindings.ts.