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];
```

*/
var ReactTestUtils = {
  renderIntoDocument: function(instance) {
    var div = document.createElement('div');
    
    
    
    
    
    return ReactDOM.render(instance, div);
  },
  isElement: function(element) {
    return ReactElement.isValidElement(element);
  },
  isElementOfType: function(inst, convenienceConstructor) {
    return (
      ReactElement.isValidElement(inst) &&
      inst.type === convenienceConstructor
    );
  },
  isDOMComponent: function(inst) {
    return !!(inst && inst.nodeType === 1 && inst.tagName);
  },
  isDOMComponentElement: function(inst) {
    return !!(inst &&
              ReactElement.isValidElement(inst) &&
              !!inst.tagName);
  },
  isCompositeComponent: function(inst) {
    if (ReactTestUtils.isDOMComponent(inst)) {