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];
```

)).toBe('download="false"');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'download',
        undefined
      )).toBe('');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'download',
        null
      )).toBe('');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'download',
        0
      )).toBe('download="0"');
    });
    it('should create markup for custom attributes', function() {
      expect(DOMPropertyOperations.createMarkupForProperty(
        'aria-label',
        'simple'
      )).toBe('aria-label="simple"');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'aria-label',
        false
      )).toBe('aria-label="false"');
      expect(DOMPropertyOperations.createMarkupForProperty(
        'aria-label',
        null
      )).toBe('');
    });
    it('should create markup for numeric properties', function() {
      expect(DOMPropertyOperations.createMarkupForProperty(