[js/webgpu] Fix Conv2DTransposeMatMul f16 compilation failure (#19596)

This is used in sam-h-decoder-f16.

### Description
<!-- Describe your changes. -->



### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->

js/web/lib/wasm/jsep/webgpu/ops/3rd-party/conv_backprop_mm_webgpu.ts

@@ -23,17 +23,17 @@ import {DataType} from '../../../../wasm-common';
 import {LOG_DEBUG} from '../../../log';
 import {TensorView} from '../../../tensor-view';
 import {ProgramInfo, ProgramInputTensorInfoDependency, ProgramUniform} from '../../types';
-import {createTensorShapeVariables, inputVariable, outputVariable, ShaderHelper, UniformsArrayType} from '../common';
+import {createTensorShapeVariables, inputVariable, outputVariable, ShaderHelper, tensorTypeToWsglStorageType, UniformsArrayType} from '../common';
 import {ConvTransposeAttributes} from '../conv-transpose';
 import {appendActivationUniforms, appendActivationUniformsData, getActivationSnippet} from '../fuse-utils';
 
-import {biasSnippet, typeSnippet} from './activation_util';
+import {biasSnippet} from './activation_util';
 import {utilFunctions} from './conv_util';
 import {makeMatMulPackedSource, makeMatMulPackedVec4Source} from './matmul_packed_webgpu';
 
 const conv2dTransposeCommonSnippet =
-    (isChannelsLast: boolean, addBias = false, attributes: ConvTransposeAttributes, innerElementSize = 4): string => {
-      const type = typeSnippet(innerElementSize, 'f32');
+    (isChannelsLast: boolean, addBias = false, attributes: ConvTransposeAttributes, type: string,
+     innerElementSize = 4): string => {
       const getWSnippet = (innerElementSize: number) => {
         switch (innerElementSize) {
           case 1:
@@ -47,7 +47,7 @@ const conv2dTransposeCommonSnippet =
             let v1 = w[getIndexFromCoords4D(coord1, vec4<i32>(uniforms.w_shape))];
             let v2 = w[getIndexFromCoords4D(coord2, vec4<i32>(uniforms.w_shape))];
             let v3 = w[getIndexFromCoords4D(coord3, vec4<i32>(uniforms.w_shape))];
-            return vec4<f32>(v0, v1, v2, v3);
+            return ${type}(v0, v1, v2, v3);
             `;
           default:
             throw new Error(`innerElementSize ${innerElementSize} is not supported.`);
@@ -224,7 +224,7 @@ export const createConv2DTransposeMatMulProgramInfo =
           const bias = inputVariable('bias', inputs[2].dataType, inputs[2].dims.length, components);
           inputVariables.push(bias);
           declareFunctions += `
-          fn getBiasByOutputCoords(coords : vec4<i32>) -> ${isVec4 ? 'vec4<f32>' : 'f32'} {
+          fn getBiasByOutputCoords(coords : vec4<i32>) -> ${bias.type.value} {
             return bias[coords.${isChannelsLast ? 'w' : 'y'}${isVec4 ? '/ 4' : ''}];
           }`;
         }
@@ -236,16 +236,20 @@ export const createConv2DTransposeMatMulProgramInfo =
           {name: 'pads', type: 'i32', length: pads.length}
         ];
         appendActivationUniforms(attributes, uniforms);
+        const elemType = tensorTypeToWsglStorageType(inputs[0].dataType, 1);
+        if (elemType !== 'f16' && elemType !== 'f32') {
+          throw new Error(`elemType ${elemType} is not supported.`);
+        }
         return `
         ${utilFunctions('uniforms.result_strides')}
         ${shaderHelper.registerUniforms(uniforms).declareVariables(...inputVariables, output)};
         ${declareFunctions}
-        ${conv2dTransposeCommonSnippet(isChannelsLast, hasBias, attributes, innerElementSize)}
+        ${conv2dTransposeCommonSnippet(isChannelsLast, hasBias, attributes, x.type.value, innerElementSize)}
         ${
             isVec4 ? makeMatMulPackedVec4Source(
-                         elementsPerThread, workGroupSize, 'f32', undefined, !isChannelsLast, tileInner) :
+                         elementsPerThread, workGroupSize, elemType, undefined, !isChannelsLast, tileInner) :
                      makeMatMulPackedSource(
-                         elementsPerThread, workGroupSize, 'f32', undefined, !isChannelsLast, tileInner, false,
+                         elementsPerThread, workGroupSize, elemType, undefined, !isChannelsLast, tileInner, false,
                          undefined, sequentialAccessByThreads)}`;
       };