We used to throw if event listener is not a function in Stack:

```js
ReactDOM.render(
  <h1 onClick={{}}>Hello World!</h1>,
  document.getElementById('container')
);
```

<img width="565" alt="screen shot 2017-08-08 at 3 41 08 pm" src="https://user-images.githubusercontent.com/810438/29077502-2646412e-7c50-11e7-8c99-3b7f6c0a2589.png">

Fiber silently ignores this.

I think we should throw. This would let us add support for objects (e.g. for passive listener configuration) if we want to in a minor rather than a major.
expect(node.hasAttribute('foo')).toBe(false);
      expect(node.getAttribute('bar')).toBe('buzz');
    });
    it('should clear a single style prop when changing `style`', () => {
      var styles = {display: 'none', color: 'red'};
      var container = document.createElement('div');
      ReactDOM.render(<div style={styles} />, container);
      var stubStyle = container.firstChild.style;
      styles = {color: 'green'};
      ReactDOM.render(<div style={styles} />, container);
      expect(stubStyle.display).toEqual('');
      expect(stubStyle.color).toEqual('green');
    });
    it('should reject attribute key injection attack on markup', () => {
      spyOn(console, 'error');
      for (var i = 0; i < 3; i++) {
        var container = document.createElement('div');
        var element = React.createElement(
          'x-foo-component',
          {'blah" onclick="beevil" noise="hi': 'selected'},
          null,
        );
        ReactDOM.render(element, container);
      }
      expectDev(console.error.calls.count()).toBe(1);
      expectDev(console.error.calls.argsFor(0)[0]).toEqual(
        'Warning: Invalid attribute name: `blah" onclick="beevil" noise="hi`',
      );
    });
    it('should reject attribute key injection attack on update', () => {