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];
```

dispatchConfig,
      ReactDOMComponentTree.getInstanceFromNode(node),
      fakeNativeEvent,
      node
    );
    
    
    event.persist();
    Object.assign(event, eventData);
    if (dispatchConfig.phasedRegistrationNames) {
      EventPropagators.accumulateTwoPhaseDispatches(event);
    } else {
      EventPropagators.accumulateDirectDispatches(event);
    }
    ReactUpdates.batchedUpdates(function() {
      EventPluginHub.enqueueEvents(event);
      EventPluginHub.processEventQueue(true);
    });
  };
}
function buildSimulators() {
  ReactTestUtils.Simulate = {};
  var eventType;
  for (eventType in EventPluginRegistry.eventNameDispatchConfigs) {
    /**
     * @param {!Element|ReactDOMComponent} domComponentOrNode
     * @param {?object} eventData Fake event data to use in SyntheticEvent.
     */
    ReactTestUtils.Simulate[eventType] = makeSimulator(eventType);
  }