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];
```

/**
 * @class ReactTestUtils
 */
function findAllInRenderedTreeInternal(inst, test) {
  if (!inst || !inst.getPublicInstance) {
    return [];
  }
  var publicInst = inst.getPublicInstance();
  var ret = test(publicInst) ? [publicInst] : [];
  var currentElement = inst._currentElement;
  if (ReactTestUtils.isDOMComponent(publicInst)) {
    var renderedChildren = inst._renderedChildren;