Merge pull request rails#6630 from route/logger_in_metal

Metal controller doesn't have logger method, check it and then delegate

actionpack/lib/action_view/helpers/controller_helper.rb

@@ -10,14 +10,20 @@ module ControllerHelper #:nodoc:
       delegate :request_forgery_protection_token, :params, :session, :cookies, :response, :headers,
                :flash, :action_name, :controller_name, :controller_path, :to => :controller
 
-      delegate :logger, :to => :controller, :allow_nil => true
-
       def assign_controller(controller)
         if @_controller = controller
           @_request = controller.request if controller.respond_to?(:request)
           @_config  = controller.config.inheritable_copy if controller.respond_to?(:config)
         end
       end
+
+      def logger
+        if controller.respond_to?(:logger)
+          controller.logger
+        else
+          nil
+        end
+      end
     end
   end
 end