Revert "Move setting content_type to AV"

This reverts commit f4d602aff6cec80304b131ecfcc2676d0304f0cc.

actionpack/lib/action_controller/metal/rendering.rb

@@ -12,6 +12,7 @@ module ActionController
     def render(*args) #:nodoc:
       raise ::AbstractController::DoubleRenderError if response_body
       super
+      self.content_type ||= Mime[lookup_context.rendered_format].to_s
       response_body
     end
 

actionview/lib/action_view/railtie.rb

@@ -38,7 +38,7 @@ module ActionView
 
     initializer "action_view.setup_action_pack", before: :add_view_paths do |app|
       ActiveSupport.on_load(:action_controller) do
-        #ActionController::Base.superclass.send(:include, ActionView::Layouts)
+        ActionController::Base.superclass.send(:include, ActionView::Layouts)
       end
     end
 

actionview/lib/action_view/rendering.rb

@@ -82,8 +82,6 @@ module ActionView
       super(*args, &block)
 
       options = _normalize_render(*args, &block)
-
-      self.content_type ||= Mime[lookup_context.rendered_format].to_s
       self.response_body = render_to_body(options)
     end