Ask the view for its method container

Rather than doing is_a? checks, ask the view object for its compiled
method container.  This gives us the power to replace the method
container depending on the instance of the view.

actionview/lib/action_view/base.rb

@@ -224,6 +224,10 @@ def run(method, locals, buffer, &block)
       @output_buffer, @virtual_path = _old_output_buffer, _old_virtual_path
     end
 
+    def compiled_method_container
+      CompiledTemplates
+    end
+
     ActiveSupport.run_load_hooks(:action_view, self)
   end
 end

actionview/lib/action_view/template.rb

@@ -264,11 +264,7 @@ def compile!(view)
           # re-compilation
           return if @compiled
 
-          if view.is_a?(ActionView::CompiledTemplates)
-            mod = ActionView::CompiledTemplates
-          else
-            mod = view.singleton_class
-          end
+          mod = view.compiled_method_container
 
           instrument("!compile_template") do
             compile(mod)