message: Turn on usage of spvc by default
  The CTS has been changed to use the version of SPIR-V that spvc is
  expecting, so the issues that previously caused a rollback should no
  longer occur.
diff: @@ -696,6 +696,7 @@ namespace dawn_native {
  void DeviceBase::SetDefaultToggles() {
  // Sets the default-enabled toggles
  mTogglesSet.SetToggle(Toggle::LazyClearResourceOnFirstUse, true);
  + mTogglesSet.SetToggle(Toggle::UseSpvc, true);
  }
  // Implementation details of object creation
  