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.
}).toThrowError(
        '`props.dangerouslySetInnerHTML` must be in the form `{__html: ...}`. ' +
          'Please visit https://fb.me/react-invariant-dangerously-set-inner-html for more information.',
      );
    });
    it('should allow {__html: null}', () => {
      expect(function() {
        mountComponent({dangerouslySetInnerHTML: {__html: null}});
      }).not.toThrow();
    });
    it('should warn about contentEditable and children', () => {
      spyOn(console, 'error');
      mountComponent({contentEditable: true, children: ''});
      expectDev(console.error.calls.count()).toBe(1);
      expectDev(console.error.calls.argsFor(0)[0]).toContain('contentEditable');
    });
    it('should respect suppressContentEditableWarning', () => {
      spyOn(console, 'error');
      mountComponent({
        contentEditable: true,
        children: '',
        suppressContentEditableWarning: true,
      });
      expectDev(console.error.calls.count()).toBe(0);
    });
    it('should validate against invalid styles', () => {
      expect(function() {
        mountComponent({style: 'display: none'});
      }).toThrowError(
        'The `style` prop expects a mapping from style properties to values, ' +