Revert "Merge pull request #12443 from arthurnn/add_inverse_of_add_target"

This reverts commit 7ed5bdc834, reversing
changes made to 31c79e291f.

Reason: this caused a regression when the associated record is creted in
a before_create callback.

See https://github.com/rails/rails/pull/12413#issuecomment-25848163

activerecord/lib/active_record/associations/collection_association.rb

@@ -350,7 +350,6 @@ module ActiveRecord
         end
 
         callback(:after_add, record)
-        set_inverse_instance(record)
 
         record
       end

activerecord/test/cases/associations/inverse_associations_test.rb

@@ -290,19 +290,6 @@ class InverseHasManyTests < ActiveRecord::TestCase
   def test_trying_to_use_inverses_that_dont_exist_should_raise_an_error
     assert_raise(ActiveRecord::InverseOfAssociationNotFoundError) { Man.find(:first).secret_interests }
   end
-
-  def test_child_instance_should_point_to_parent_without_saving
-    man = Man.new
-    i = Interest.create(:topic => 'Industrial Revolution Re-enactment')
-
-    man.interests << i
-    assert_not_nil i.man
-
-    i.man.name = "Charles"
-    assert_equal i.man.name, man.name
-
-    assert !man.persisted?
-  end
 end
 
 class InverseBelongsToTests < ActiveRecord::TestCase