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.
'Warning: Invalid DOM property `class`. Did you mean `className`?\n    in div (at **)',
      );
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
        'Warning: Unknown event handler property `onclick`. Did you mean ' +
          '`onClick`?\n    in input (at **)',
      );
    });
    it('gives source code refs for unknown prop warning (ssr)', () => {
      spyOn(console, 'error');
      ReactDOMServer.renderToString(<div class="paladin" />);
      ReactDOMServer.renderToString(<input type="text" onclick="1" />);
      expectDev(console.error.calls.count()).toBe(2);
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: Invalid DOM property `class`. Did you mean `className`?\n    in div (at **)',
      );
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
        'Warning: Unknown event handler property `onclick`. Did you mean ' +
          '`onClick`?\n    in input (at **)',
      );
    });
    it('gives source code refs for unknown prop warning for update render', () => {
      spyOn(console, 'error');
      var container = document.createElement('div');
      ReactTestUtils.renderIntoDocument(<div className="paladin" />, container);
      expectDev(console.error.calls.count()).toBe(0);
      ReactTestUtils.renderIntoDocument(<div class="paladin" />, container);
      expectDev(console.error.calls.count()).toBe(1);
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: Invalid DOM property `class`. Did you mean `className`?\n    in div (at **)',
      );