Fixed implementation of expandRowForItem:withRowAnimation: method.
Fixed implementation of expandRowForItem:withRowAnimation: method.

Fixed crash when expanding expanded rows.

ivulyov/RATreeView,wenxp/RATreeView,benzhipeng/RATreeView,cnbin/RATreeView,tuanphung/RATreeView,200895045/RATreeView,AlexanderMazaletskiy/RATreeView,treejames/RATreeView,ideacp/RATreeView,zuojx1013/RATreeView,chenkaige/RATreeView,Nirvana-icy/RATreeView