Add support for CollectionAssociation#delete by Fixnum or String

I found the next issue between CollectionAssociation `delete`
and `destroy`.

    class Person < ActiveRecord::Base
      has_many :pets
    end

    person.pets.destroy(1)
    # => OK, returns the destroyed object

    person.pets.destroy("2")
    # => OK, returns the destroyed object

    person.pets.delete(1)
    # => ActiveRecord::AssociationTypeMismatch

    person.pets.delete("2")
    # => ActiveRecord::AssociationTypeMismatch

Adding support for deleting with a fixnum or string like
`destroy` method.

1 files changed, 17 insertions, 3 deletions

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 8b384c2513..0d8f311117 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -936,10 +936,24 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 2, summit.client_of
   end
 
-  def test_deleting_type_mismatch
+  def test_deleting_by_fixnum_id
     david = Developer.find(1)
-    david.projects.reload
-    assert_raise(ActiveRecord::AssociationTypeMismatch) { david.projects.delete(1) }
+
+    assert_difference 'david.projects.count', -1 do
+      assert_equal 1, david.projects.delete(1).size
+    end
+
+    assert_equal 1, david.projects.size
+  end
+
+  def test_deleting_by_string_id
+    david = Developer.find(1)
+
+    assert_difference 'david.projects.count', -1 do
+      assert_equal 1, david.projects.delete('1').size
+    end
+
+    assert_equal 1, david.projects.size
   end
 
   def test_deleting_self_type_mismatch