The error event on `<source>` elements doesn't work. Looking at #4370, it seems like there is an `onError` for `<video>` but I can't tell if that's supposed to work for `<source>` too.

The error event is useful so I can deduce which format the browser is using.

break;
      case 'button':
        props = ReactDOMButton.getHostProps(this, props, hostParent);
        break;
      case 'input':
        ReactDOMInput.mountWrapper(this, props, hostParent);
        props = ReactDOMInput.getHostProps(this, props);
        transaction.getReactMountReady().enqueue(trackInputValue, this);
        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
        break;
      case 'option':
        ReactDOMOption.mountWrapper(this, props, hostParent);
        props = ReactDOMOption.getHostProps(this, props);
        break;
      case 'select':
        ReactDOMSelect.mountWrapper(this, props, hostParent);
        props = ReactDOMSelect.getHostProps(this, props);
        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
        break;
      case 'textarea':
        ReactDOMTextarea.mountWrapper(this, props, hostParent);
        props = ReactDOMTextarea.getHostProps(this, props);
        transaction.getReactMountReady().enqueue(trackInputValue, this);
        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
        break;
    }
    assertValidProps(this, props);
    
    
    var namespaceURI;