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];
```

});
      it('gets recorded during an update from children', () => {
        var node = document.createElement('div');
        ReactDOM.render(<div><span /><p /></div>, node);
        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
        ReactNativeOperationHistoryDevtool.clearHistory();
        ReactDOM.render(<div>Bye.</div>, node);
        assertHistoryMatches([{
          instanceID: inst._debugID,
          type: 'remove child',
          payload: {fromIndex: 0},
        }, {
          instanceID: inst._debugID,
          type: 'remove child',
          payload: {fromIndex: 1},
        }, {
          instanceID: inst._debugID,
          type: 'replace text',
          payload: 'Bye.',
        }]);
      });
      it('gets ignored if new text is equal', () => {
        var node = document.createElement('div');
        ReactDOM.render(<div>Hi.</div>, node);
        ReactNativeOperationHistoryDevtool.clearHistory();
        ReactDOM.render(<div>Hi.</div>, node);
        assertHistoryMatches([]);
      });
    });
    describe('text node', () => {