message: Stop using SPVC by default.
  SPVC only allows SPIR-V 1.0 while WebGPU samples and other existing
  content outputs SPIR-V 1.3. Turning SPVC on by default broke all of
  them, so we disable SPVC until we decide what to do.
diff: @@ -696,7 +696,7 @@ namespace dawn_native {
  void DeviceBase::SetDefaultToggles() {
  // Sets the default-enabled toggles
  mTogglesSet.SetToggle(Toggle::LazyClearResourceOnFirstUse, true);
  - mTogglesSet.SetToggle(Toggle::UseSpvc, true);
  + mTogglesSet.SetToggle(Toggle::UseSpvc, false);
  }
  // Implementation details of object creation
  