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.
expectDev(console.log.calls.count()).toBe(2);
      expectDev(console.log.calls.argsFor(0)[0]).toContain('onError called');
      expectDev(console.log.calls.argsFor(1)[0]).toContain('onLoad called');
    });
  });
  describe('updateComponent', () => {
    var container;
    beforeEach(() => {
      container = document.createElement('div');
    });
    it('should warn against children for void elements', () => {
      ReactDOM.render(<input />, container);
      expect(function() {
        ReactDOM.render(<input>children</input>, container);
      }).toThrowError(
        'input is a void element tag and must neither have `children` nor use ' +
          '`dangerouslySetInnerHTML`.',
      );
    });
    it('should warn against dangerouslySetInnerHTML for void elements', () => {
      ReactDOM.render(<input />, container);
      expect(function() {
        ReactDOM.render(
          <input dangerouslySetInnerHTML={{__html: 'content'}} />,
          container,
        );
      }).toThrowError(
        'input is a void element tag and must neither have `children` nor use ' +
          '`dangerouslySetInnerHTML`.',
      );