fix ruby syntax in comments for the JavascriptGenerator (closes #4577) [Rick]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4146 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_view/helpers/prototype_helper.rb

@@ -425,7 +425,7 @@ def include_helpers_from_context
         #
         #   # Controller action
         #   def poll
-        #     render :update { |page| page.update_time }
+        #     render(:update) { |page| page.update_time }
         #   end
         #
         # You can also use PrototypeHelper#update_page_tag instead of