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.

var container = document.createElement('div');
      ReactDOM.render(<div style={styles} />, container);
      var stubStyle = container.firstChild.style;
      styles = {display: 'block'};
      ReactDOM.render(<div style={styles} />, container);
      expect(stubStyle.display).toEqual('block');
    });
    it('should update styles if updated to null multiple times', function() {
      var styles = null;
      var container = document.createElement('div');
      ReactDOM.render(<div style={styles} />, container);
      styles = {display: 'block'};
      var stubStyle = container.firstChild.style;
      ReactDOM.render(<div style={styles} />, container);
      expect(stubStyle.display).toEqual('block');
      ReactDOM.render(<div style={null} />, container);
      expect(stubStyle.display).toEqual('');
      ReactDOM.render(<div style={styles} />, container);
      expect(stubStyle.display).toEqual('block');
      ReactDOM.render(<div style={null} />, container);
      expect(stubStyle.display).toEqual('');
    });
    it('should skip reserved props on web components', function() {
      var container = document.createElement('div');
      ReactDOM.render(
        <my-component
          children={['foo']}
          suppressContentEditableWarning={true}
        />,
        container