Only undef deprecated methods if they still exist. Gone in 4.1/master.

Author: jeremy

lib/prototype-rails/javascript_helper.rb

@@ -2,8 +2,8 @@
 
 ActionView::Helpers::JavaScriptHelper.module_eval do
   include ActionView::Helpers::PrototypeHelper
-  undef_method :button_to_function
-  undef_method :link_to_function
+  undef_method :button_to_function if method_defined? :button_to_function
+  undef_method :link_to_function if method_defined? :link_to_function
 
   # Returns a button with the given +name+ text that'll trigger a JavaScript +function+ using the
   # onclick handler.