remove condition since to_time always available in ruby19 DateTime

activesupport/lib/active_support/core_ext/date_time/conversions.rb

@@ -6,7 +6,7 @@
 class DateTime
   # Ruby 1.9 has DateTime#to_time which internally relies on Time. We define our own #to_time which allows
   # DateTimes outside the range of what can be created with Time.
-  remove_method :to_time if instance_methods.include?(:to_time)
+  remove_method :to_time
 
   # Convert to a formatted string. See Time::DATE_FORMATS for predefined formats.
   #