Fix Focusable To Remove _onFocus() When Unmounting
Fix Focusable To Remove _onFocus() When Unmounting

Fix the Focusable to remove _onFocus() when unmounting for all DOM
elements that uses EventTarget in order to remove all _onFocus() from
the DOM tree when the user leaves the section.

TouchBistro/frig,TouchBistro/frig,frig-js/frig,frig-js/frig