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];
```

});
  describe('deleteValueForProperty', function() {
    var stubNode;
    beforeEach(function() {
      stubNode = document.createElement('div');
      ReactDOMComponentTree.precacheNode({}, stubNode);
    });
    it('should remove attributes for normal properties', function() {
      DOMPropertyOperations.setValueForProperty(stubNode, 'title', 'foo');
      expect(stubNode.getAttribute('title')).toBe('foo');
      expect(stubNode.title).toBe('foo');
      DOMPropertyOperations.deleteValueForProperty(stubNode, 'title');
      expect(stubNode.getAttribute('title')).toBe(null);
      
      
    });
    it('should not remove attributes for special properties', function() {
      stubNode = document.createElement('input');
      ReactDOMComponentTree.precacheNode({}, stubNode);
      stubNode.setAttribute('value', 'foo');
      DOMPropertyOperations.deleteValueForProperty(stubNode, 'value');
      
      
      expect(stubNode.value).toBe('');
    });
    it('should not leave all options selected when deleting multiple', function() {
      stubNode = document.createElement('select');
      ReactDOMComponentTree.precacheNode({}, stubNode);
      stubNode.multiple = true;
      stubNode.appendChild(document.createElement('option'));