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)

var measurements = measure(fn);
    var summary = ReactDefaultPerf.getWasted(measurements);
    expect(summary).toEqual([]);
  }
  it('should not count initial render as waste', function() {
    expectNoWaste(() => {
      ReactTestUtils.renderIntoDocument(<App />);
    });
  });
  it('should not count unmount as waste', function() {
    var container = document.createElement('div');
    ReactDOM.render(<Div>hello</Div>, container);
    expectNoWaste(() => {
      ReactDOM.unmountComponentAtNode(container);
    });
  });
  it('should not count content update as waste', function() {
    var container = document.createElement('div');
    ReactDOM.render(<Div>hello</Div>, container);
    expectNoWaste(() => {
      ReactDOM.render(<Div>hello world</Div>, container);
    });
  });
  it('should not count child addition as waste', function() {
    var container = document.createElement('div');