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.
nextProps.hasOwnProperty(propKey) ||
        !lastProps.hasOwnProperty(propKey) ||
        lastProps[propKey] == null
      ) {
        continue;
      }
      if (propKey === STYLE) {
        var lastStyle = lastProps[propKey];
        for (styleName in lastStyle) {
          if (lastStyle.hasOwnProperty(styleName)) {
            if (!styleUpdates) {
              styleUpdates = {};
            }
            styleUpdates[styleName] = '';
          }
        }
      } else if (
        propKey === DANGEROUSLY_SET_INNER_HTML ||
        propKey === CHILDREN
      ) {
        
      } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
        
      } else if (registrationNameModules.hasOwnProperty(propKey)) {
        
        
        
        if (!updatePayload) {