Use 32-bit element size for making heap view of requiredFeatures

- This commit fixes adapter.requestDevice for wasm64 by using the
  correct factor to calculate the end of the view in HEAPU32 from
  requiredFeaturesPtr. Earlier, the returned array was twice the
  actual size.

Author: jspanchu

src/library_webgpu.js

@@ -2645,7 +2645,8 @@ var LibraryWebGPU = {
       var requiredFeatureCount = {{{ gpu.makeGetU32('descriptor', C_STRUCTS.WGPUDeviceDescriptor.requiredFeatureCount) }}};
       if (requiredFeatureCount) {
         var requiredFeaturesPtr = {{{ makeGetValue('descriptor', C_STRUCTS.WGPUDeviceDescriptor.requiredFeatures, '*') }}};
-        desc["requiredFeatures"] = Array.from({{{ makeHEAPView('32', 'requiredFeaturesPtr', `requiredFeaturesPtr + requiredFeatureCount * ${POINTER_SIZE}`) }}},
+        // requiredFeaturesPtr is a pointer to an array of FeatureName which is an enum of size uint32_t
+        desc["requiredFeatures"] = Array.from({{{ makeHEAPView('U32', 'requiredFeaturesPtr', `requiredFeaturesPtr + requiredFeatureCount * 4`) }}},
           (feature) => WebGPU.FeatureName[feature]);
       }
       var requiredLimitsPtr = {{{ makeGetValue('descriptor', C_STRUCTS.WGPUDeviceDescriptor.requiredLimits, '*') }}};