QmlDesigner.model: Remove unused code

Change-Id: Id4b8a2c9f1bc687fea48094d92763261a385bcf4
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner.Rewriter: Supporting Tab contents as implicit component

Because of the alias we get the cpp type.

Change-Id: Iad82fa702940978b555734af4496c1c49b49f3f8
Reviewed-by: Marco Bubke <marco.bubke@digia.com>