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.
continue;
      }
      var nextProp = rawProps[propKey];
      if (propKey === CHILDREN) {
        
        
        
        
        
        
        
        
        
        if (typeof nextProp === 'string') {
          if (domElement.textContent !== nextProp) {
            if (__DEV__) {
              warnForTextDifference(domElement.textContent, nextProp);
            }
            updatePayload = [CHILDREN, nextProp];
          }
        } else if (typeof nextProp === 'number') {
          if (domElement.textContent !== '' + nextProp) {