Element: Add unit tests for focusin/focusout hack

Follows-up 33c379f.

Change-Id: I396093dfa813480df7b1675f366ace6ac8bf85b5
Element: Remove focusin/focusout hack in onDOMEvent

Follows-up 33c379f, e3a09eb:
- http://bugs.jquery.com/ticket/14180
- https://github.com/jquery/jquery/commit/1cecf64e5aa4153
- http://blog.jquery.com/2014/01/24/jquery-1-11-and-2-1-released/
  Fixed:
  * #14180: focusin/out special events don’t work cross-window

Now that we've upgraded to jQuery 1.11, this hack is obsolete.

Change-Id: I0cfaaaa039980e2827130069262cbd69297ce5ba
Merge "Element: Add unit tests for focusin/focusout hack"
Merge "Element: Remove focusin/focusout hack in onDOMEvent"