Add Uint32Array overload for setBindGroup (gpuweb#440)

This is useful to reduce bindings overhead in type conversion from
passing a vanilla JavaScript array. WebAssembly applications will use
this API to efficiently pass data in the WASM heap to WebGPU.

The overload has arguments dynamicOffsetsDataStart and
dynamicOffsetsDataLength which specify a subregion in the Uint32Array
to read from.

spec/index.bs

@@ -1654,6 +1654,11 @@ interface mixin GPUProgrammablePassEncoder {
     void setBindGroup(unsigned long index, GPUBindGroup bindGroup,
                       optional sequence<unsigned long> dynamicOffsets = []);
 
+    void setBindGroup(unsigned long index, GPUBindGroup bindGroup,
+                      Uint32Array dynamicOffsetsData,
+                      unsigned long long dynamicOffsetsDataStart,
+                      unsigned long long dynamicOffsetsDataLength);
+
     void pushDebugGroup(DOMString groupLabel);
     void popDebugGroup();
     void insertDebugMarker(DOMString markerLabel);