Revert "Merge pull request #19685 from vngrs/actionview_parent_layout_bug"

This reverts commit a9d58c77da, reversing
changes made to 041c2c879a.

Reason: The old behavior is how it was working in previous version of
Rails since 4.0.x so it is not safe to backport to a stable branch.

See https://github.com/rails/rails/issues/19626#issuecomment-89862258
and https://github.com/rails/rails/pull/15050#issuecomment-45333449

actionview/lib/action_view/layouts.rb

@@ -315,14 +315,6 @@ module ActionView
             name_clause
         end
 
-        if self._layout_conditions.empty?
-          self.class_eval <<-RUBY, __FILE__, __LINE__ + 1
-            def _layout
-              #{layout_definition}
-            end
-            private :_layout
-          RUBY
-        else
         self.class_eval <<-RUBY, __FILE__, __LINE__ + 1
           def _layout
             if _conditional_layout?
@@ -334,7 +326,6 @@ module ActionView
           private :_layout
         RUBY
       end
-      end
 
       private
 

actionview/test/actionpack/controller/layout_test.rb

@@ -122,14 +122,6 @@ class PrependsViewPathController < LayoutTest
   end
 end
 
-class ParentController < LayoutTest
-  layout 'item'
-end
-
-class ChildController < ParentController
-  layout 'layout_test', only: :hello
-end
-
 class OnlyLayoutController < LayoutTest
   layout 'item', :only => "hello"
 end
@@ -233,12 +225,6 @@ class LayoutSetInResponseTest < ActionController::TestCase
     get :hello
     assert_equal "layout_test.erb hello.erb", @response.body.strip
   end
-
-  def test_respect_to_parent_layout
-    @controller = ChildController.new
-    get :goodbye
-    assert_includes @response.body, 'item.erb'
-  end
 end
 
 class SetsNonExistentLayoutFile < LayoutTest