rails/rails — pull request #5720 by kennyj (2012-04-03 16:25:05+00:00)
Title: Get a properly aliased_table_name, when we use a polymorphic association.

According to ActiveRecord::Associations::BelongsToPolymorphicAssociation, we override *klass* method.
We get a properly aliased_table_name, when we use a polymorphic association and this method.