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.

ReactDOMServer.renderToStaticMarkup(
          React.DOM.div({
            title: '\'"<>&',
            style: {
              textAlign: '\'"<>&',
            },
          }, '\'"<>&')
        )
      ).toBe(
        '<div title="&#x27;&quot;&lt;&gt;&amp;" style="text-align:&#x27;&quot;&lt;&gt;&amp;;">' +
          '&#x27;&quot;&lt;&gt;&amp;' +
        '</div>'
      );
    });
  });
  describe('unmountComponent', function() {
    it('should clean up listeners', function() {
      var EventPluginHub = require('EventPluginHub');
      var ReactDOMComponentTree = require('ReactDOMComponentTree');
      var container = document.createElement('div');
      document.body.appendChild(container);
      var callback = function() {};
      var instance = <div onClick={callback} />;
      instance = ReactDOM.render(instance, container);
      var rootNode = ReactDOM.findDOMNode(instance);
      var inst = ReactDOMComponentTree.getInstanceFromNode(rootNode);
      expect(
        EventPluginHub.getListener(inst, 'onClick')
      ).toBe(callback);
      expect(rootNode).toBe(ReactDOM.findDOMNode(instance));