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];
```

console.table = () => {};
      console.table.isFake = true;
    }
    React = require('React');
    ReactDOM = require('ReactDOM');
    ReactPerf = require('ReactPerf');
    ReactTestUtils = require('ReactTestUtils');
    App = React.createClass({
      render: function() {
        return <div><Box /><Box flip={this.props.flipSecond} /></div>;
      },
    });
    Box = React.createClass({
      render: function() {
        return <div key={!!this.props.flip}><input /></div>;
      },
    });
    
    Div = React.createClass({
      render: function() {
        return <div {...this.props} />;
      },
    });
  });
  afterEach(function() {
    if (console.table.isFake) {
      delete console.table;
    }
  });
  function measure(fn) {