Use .focus() instead of target.focus() for quirks test

I am using this plugin in node with jsdom and using the plain `target` throws an error in bililiteRange.js:
```
TypeError: Cannot call method 'replace' of null
```

It traces back to the line I have changed in the commit. I guess the issue is that pure dom elements do not automatically get a focus method with jsdom. However, using the jquery object eliminates this problem.