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.
'of <p>.' +
          addendum,
      );
    });
    it('warns nicely for table rows', () => {
      spyOn(console, 'error');
      class Row extends React.Component {
        render() {
          return <tr>x</tr>;
        }
      }
      class Foo extends React.Component {
        render() {
          return <table><Row /> </table>;
        }
      }
      ReactTestUtils.renderIntoDocument(<Foo />);
      expectDev(console.error.calls.count()).toBe(3);
      var addendum1 = ReactDOMFeatureFlags.useFiber
        ? '\n    in tr (at **)' +
            '\n    in Row (at **)' +
            '\n    in table (at **)' +
            '\n    in Foo (at **)'
        : ' See Foo > table > Row > tr.';
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: validateDOMNesting(...): <tr> cannot appear as a child of ' +
          '<table>. Add a <tbody> to your code to match the DOM tree generated ' +
          'by the browser.' +
          addendum1,
      );