Given the following test case

``` jsx
function TestCmp() {
  return <span>{NaN}</span>;
}

ReactDOM.render(<TestCmp />, document.getElementById('app'));
```

Produces the following warning:

```
Warning: Component's children should not be mutated.
    in span (created by TestCmp)
    in TestCmp (created by Unknown)
```

This is probably caused by [this mutation check](https://github.com/facebook/react/blob/328fc75bc910032ff37dc9d93429fb14b476bd0d/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js#L34), which was introduced in 15.3.0, but it doesn't work for NaN, because NaN != NaN

for (var i = 0; i < hooks.length; i++) {
    var hook = hooks[i];
    var fn = hook[event];
    if (fn) {
      callHook(event, fn, hook, arg1, arg2, arg3, arg4, arg5);
    }
  }
}
var isProfiling = false;
var flushHistory = [];
var lifeCycleTimerStack = [];
var currentFlushNesting = 0;
var currentFlushMeasurements = [];
var currentFlushStartTime = 0;
var currentTimerDebugID = null;
var currentTimerStartTime = 0;
var currentTimerNestedFlushDuration = 0;
var currentTimerType = null;
var lifeCycleTimerHasWarned = false;
function clearHistory() {