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];
```

container.tagName.toUpperCase() !== 'BODY',
      'render(): Rendering components directly into document.body is ' +
      'discouraged, since its children are often manipulated by third-party ' +
      'scripts and browser extensions. This may lead to subtle ' +
      'reconciliation issues. Try rendering into a container element created ' +
      'for your app.'
    );
    var nextWrappedElement = ReactElement(
      TopLevelWrapper,
      null,
      null,
      null,
      null,
      null,
      nextElement
    );
    var prevComponent = getTopLevelWrapperInContainer(container);
    if (prevComponent) {
      var prevWrappedElement = prevComponent._currentElement;
      var prevElement = prevWrappedElement.props;
      if (shouldUpdateReactComponent(prevElement, nextElement)) {
        var publicInst = prevComponent._renderedComponent.getPublicInstance();
        var updatedCallback = callback && function() {
          callback.call(publicInst);
        };
        ReactMount._updateRootComponent(
          prevComponent,
          nextWrappedElement,
          container,
          updatedCallback