Calling `ReactDefaultPerf.printWasted()` results in:

```
Uncaught TypeError: Cannot read property 'forEach' of undefined
writes.(anonymous function).forEach @ ReactDefaultPerfAnalysis.js:195
Object.keys.forEach @ ReactDefaultPerfAnalysis.js:192
getUnchangedComponents @ ReactDefaultPerfAnalysis.js:191
getInclusiveSummary @ ReactDefaultPerfAnalysis.js:139
ReactDefaultPerf.getMeasurementsSummaryMap @ ReactDefaultPerf.js:118
ReactDefaultPerf.printWasted @ ReactDefaultPerf.js:133
```

(this is on a page internally at Facebook so I assume it's a fairly recent React version)

ReactDefaultPerf.start();
    fn();
    ReactDefaultPerf.stop();
    return ReactDefaultPerf.getLastMeasurements().__unstable_this_format_will_change;
  }
  it('should count no-op update as waste', function() {
    var container = document.createElement('div');
    ReactDOM.render(<App />, container);
    var measurements = measure(() => {