Fix possible AttributeError in migration code

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@43485 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Tool/TypesTool.py

@@ -360,7 +360,7 @@ class TypesTool(TypeProvider):
       trashbin._setOb(old_types_tool.id, old_types_tool)
 
   def _migrateToPortalTypeClass(self):
-    for type_definition in self.contentValues():
+    for type_definition in self.objectValues():
       type_definition._migrateToPortalTypeClass()
     return super(TypesTool, self)._migrateToPortalTypeClass()