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];
```

});
  describe('createMarkupForProperty', function() {
    it('should create markup for simple properties', function() {
      expect(DOMPropertyOperations.createMarkupForProperty(
        'name',
        'simple'
      )).toBe('name="simple"');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'name',
        false
      )).toBe('name="false"');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'name',
        null
      )).toBe('');
    });
    it('should work with the id attribute', function() {
      expect(DOMPropertyOperations.createMarkupForProperty(
        'id',
        'simple'
      )).toBe('id="simple"');
    });
    it('should create markup for boolean properties', function() {
      expect(DOMPropertyOperations.createMarkupForProperty(
        'checked',
        'simple'
      )).toBe('checked=""');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'checked',
        true