Revert "ERP5: remove duplicated code when getting transformation from a resource"

This reverts commit fba5767e.

Sorry, I went too quickly, there was difference between self and context

product/ERP5/Document/Resource.py

@@ -298,6 +298,10 @@ class Resource(XMLObject, XMLMatrix, VariatedMixin):
           return transformation_list[0].getObject()
         return None
 
+      method = context._getTypeBasedMethod('getDefaultTransformationValue')
+      if method is not None:
+        return method(context)
+
       transformation_list = self.portal_domains.searchPredicateList(context,
                                 portal_type=self.getPortalObject().getPortalTransformationTypeList(),
                                 limit=1)