React 0.14.7: `<option value="">empty</option>` emits empty string on change
http://jsbin.com/pisita/10/edit?html,js,console,output
React 15.0.0-rc.1`<option value="">empty</option>` emits string with value "empty" on change
http://jsbin.com/bemaze/12/edit?html,js,console,output
This is because React 15.0.0-rc.1 cuts off `value=""` from option tag

expect(
        EventPluginHub.getListener(inst, 'onClick')
      ).toBe(callback);
      expect(rootNode).toBe(ReactDOM.findDOMNode(instance));
      ReactDOM.unmountComponentAtNode(container);
      expect(
        EventPluginHub.getListener(inst, 'onClick')
      ).toBe(undefined);
    });
    it('should clean up input value tracking', function() {
      var container = document.createElement('div');
      var node = ReactDOM.render(<input type="text" defaultValue="foo"/>, container);
      var tracker = inputValueTracking._getTrackerFromNode(node);
      spyOn(tracker, 'stopTracking');
      ReactDOM.unmountComponentAtNode(container);
      expect(tracker.stopTracking.calls.length).toBe(1);
    });
    it('should clean up input textarea tracking', function() {
      var container = document.createElement('div');
      var node = ReactDOM.render(<textarea defaultValue="foo"/>, container);
      var tracker = inputValueTracking._getTrackerFromNode(node);
      spyOn(tracker, 'stopTracking');
      ReactDOM.unmountComponentAtNode(container);
      expect(tracker.stopTracking.calls.length).toBe(1);
    });
    it('unmounts children before unsetting DOM node info', function() {
      var Inner = React.createClass({
        render: function() {
          return <span />;
        },