genlist.edc: fixed decorate all mode bug when scrolling.
genlist.edc: fixed decorate all mode bug when scrolling.

When we scroll the genlist with decorate all mode, newerly realized items looked like a normal mode.
This was caused by a new theme. Genlist item style should handle all the necessary parts when decorate mode is enabled/diabled.
This fixes T576.

tasn/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary