The parent of instantiation of nested class of template class
should be the instantiation of enclosing template class.

Task-number: QTCREATORBUG-11752
Change-Id: I8875c738848b85731f5ea88a60da190b4b0ad18f
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>