Fix compound assignment storage_rw when resultType != storage(resultT…

…ype) (gpuweb#3846)

In the storage_rw case, when the result type is not the same as
storage(result type) then generate the full expansion (stylistically):

     var ret = LHSType(LHS);
     ret {op}= RHSType(RHS);
     outputs.value = ret;

instead of:

     outputs.value = {storageType}(LHS);
     outputs.value {op}= ret;

This situation occurs when the value type is bool or bool-vec. In
that case the result type is u32, and there are no mixed overloads for &
and | such as:

   u32 & bool
   u32 | bool

Fixes: gpuweb#3845

src/webgpu/shader/execution/expression/expression.ts

@@ -867,7 +867,7 @@ ${body}
       // Runtime eval
       //////////////////////////////////////////////////////////////////////////
       let operation = '';
-      if (inputSource === 'storage_rw') {
+      if (inputSource === 'storage_rw' && objectEquals(resultType, storageType(resultType))) {
         operation = `
         outputs[i].value = ${storageType(resultType)}(inputs[i].lhs);
         outputs[i].value ${op} ${rhsType}(inputs[i].rhs);`;