[focus][popup] fix focus related bugs

[focus][popup] fix focus related bugs

1. if user just hides the popup, the focus tree is broken. it is caused by elm_object_content_unset(notify);
   popup calls elm_object_content_set(notify, popup); in the _on_show(); it would be terrible.
   there would be a structual problem, but it is hart to figure out.

2. _elm_popup_smart_focus_direction(); calls notify's focus_direction(); and it calls popup's one again.
   there is circular dependency between notify and popup.

SVN revision: 84073