I was testing latest refactor of PerfTools.
When using printOperations() often (but not always) I get 

```
Uncaught TypeError: Cannot read property 'displayName' of undefined
```

in getOperations() on the line:

```
var {displayName, ownerID} = treeSnapshot[instanceID];
```

expectNoWaste(() => {
      ReactDOM.render(<Div>{'hello'}{'friend'}</Div>, container);
    });
  });
  it('warns once when using getMeasurementsSummaryMap', function() {
    var measurements = measure(() => {});
    spyOn(console, 'error');
    ReactPerf.getMeasurementsSummaryMap(measurements);
    expect(console.error.calls.length).toBe(1);
    expect(console.error.argsForCall[0][0]).toContain(
      '`ReactPerf.getMeasurementsSummaryMap(...)` is deprecated. Use ' +
      '`ReactPerf.getWasted(...)` instead.'
    );
    ReactPerf.getMeasurementsSummaryMap(measurements);
    expect(console.error.calls.length).toBe(1);
  });
  it('warns once when using printDOM', function() {
    var measurements = measure(() => {});
    spyOn(console, 'error');
    ReactPerf.printDOM(measurements);
    expect(console.error.calls.length).toBe(1);
    expect(console.error.argsForCall[0][0]).toContain(
      '`ReactPerf.printDOM(...)` is deprecated. Use ' +
      '`ReactPerf.printOperations(...)` instead.'
    );
    ReactPerf.printDOM(measurements);
    expect(console.error.calls.length).toBe(1);
  });
});