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.
styleUpdates = {};
              }
              styleUpdates[styleName] = nextProp[styleName];
            }
          }
        } else {
          
          if (!styleUpdates) {
            if (!updatePayload) {
              updatePayload = [];
            }
            updatePayload.push(propKey, styleUpdates);
          }
          styleUpdates = nextProp;
        }
      } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
        var nextHtml = nextProp ? nextProp[HTML] : undefined;
        var lastHtml = lastProp ? lastProp[HTML] : undefined;
        if (nextHtml != null) {
          if (lastHtml !== nextHtml) {
            (updatePayload = updatePayload || []).push(propKey, '' + nextHtml);
          }
        } else {
          
          
        }
      } else if (propKey === CHILDREN) {
        if (
          lastProp !== nextProp &&
          (typeof nextProp === 'string' || typeof nextProp === 'number')