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];
```

/**
 * Copyright 2016-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactDebugTool
 */
'use strict';
var ExecutionEnvironment = require('ExecutionEnvironment');
var performanceNow = require('performanceNow');
var warning = require('warning');
var eventHandlers = [];
var handlerDoesThrowForEvent = {};
function emitEvent(handlerFunctionName, arg1, arg2, arg3, arg4, arg5) {