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.
ReactDOM.render(
        <div dangerouslySetInnerHTML={{__html: null}} />,
        container,
      );
      expect(container.textContent).toEqual('');
      ReactDOM.render(
        <div dangerouslySetInnerHTML={{__html: undefined}} />,
        container,
      );
      expect(container.textContent).toEqual('');
    });
    it('should remove attributes', () => {
      var container = document.createElement('div');
      ReactDOM.render(<img height="17" />, container);
      expect(container.firstChild.hasAttribute('height')).toBe(true);
      ReactDOM.render(<img />, container);
      expect(container.firstChild.hasAttribute('height')).toBe(false);
    });
    it('should remove properties', () => {
      var container = document.createElement('div');
      ReactDOM.render(<div className="monkey" />, container);
      expect(container.firstChild.className).toEqual('monkey');
      ReactDOM.render(<div />, container);
      expect(container.firstChild.className).toEqual('');
    });
    it('should properly update custom attributes on custom elements', () => {
      var container = document.createElement('div');
      ReactDOM.render(<some-custom-element foo="bar" />, container);
      ReactDOM.render(<some-custom-element bar="buzz" />, container);
      var node = container.firstChild;