Move protected instance variables definition, kill compatibility module

actionpack/lib/action_controller/base.rb

@@ -228,8 +228,11 @@ def self.without_modules(*modules)
       include mod
     end
 
-    # Rails 2.x compatibility
-    include ActionController::Compatibility
+    # Define some internal variables that should not be propagated to the view.
+    self.protected_instance_variables = [
+      :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
+      :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout
+    ]
 
     ActiveSupport.run_load_hooks(:action_controller, self)
   end

actionpack/lib/action_controller/metal/compatibility.rb

-module ActionController
-  module Compatibility
-    extend ActiveSupport::Concern
-
-    # Temporary hax
-    included do
-      self.protected_instance_variables = [
-        :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
-        :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout
-      ]
-    end
-  end
-end