prevent error in non pjax onpopstate


```
.............................................TypeError: 'undefined' is not an object (evaluating 'pjax.state.id')

  http://localhost:4567/jquery.pjax.js:406 in onPjaxPopstate
  http://localhost:4567/test/jquery-1.9.0.js:3045
  http://localhost:4567/test/jquery-1.9.0.js:2721
Timeout
```

* this is throwing exception and causing tests to fall (although it doesn't break the functionality)