[Bugfix beta] fix click helper focus change issue

This hits me during my migration process from ember 1.0.0. A test in my application integration suite was failing intermitently, and after a tedious investigation and the help of @rjackson I finally find out what's happening.
After this https://github.com/emberjs/ember.js/pull/3563, it appears that when the window is not focused, then when switching from an input to an other one using the 'click' helper the first input is not focused out.

This fix works on chrome, and I don't know about firefox, since the ember test suite cannot run on my machine I have this error: 
![screenshot from 2013-12-03 09 59 22](https://f.cloud.github.com/assets/1826661/1662193/a25bbec2-5bf9-11e3-964e-1191a0dafb06.png)

All I can say is that my application integration test suite is passing on chrome, but not on FF, so I guess the fix does not work for FF.