Bug 261890

fragmentWriteGBuffers.wgsl from https://webgpu.github.io/webgpu-samples/samples/deferredRendering#fragmentWriteGBuffers.wgsl does not compile because it writes to multiple render targets and the locations are not specified. I.e., in the generated output: struct type0 { vec<float, 4> normal ; vec<float, 4> albedo ; }; should be: struct type0 { vec<float, 4> normal [[color(0)]]; vec<float, 4> albedo [[color(1)]]; };