filename option in vm.runInThisContext function argument disabled

This code: 

``` js
  vm= require('vm');
  vm.runInThisContext('console.trace()',{filename:'vmTest'});
```

gives such a output:

```
  Trace
      at [object Object]:1:9
```

But docapi says:
  filename: allows you to control the filename that shows up in any stack traces produced.
