removing 1.8 reference

activesupport/lib/active_support/core_ext/object/instance_variables.rb

 class Object
   # Returns a hash that maps instance variable names without "@" to their
-  # corresponding values. Keys are strings both in Ruby 1.8 and 1.9.
+  # corresponding values. Keys are strings.
   #
   #   class C
   #     def initialize(x, y)
@@ -13,8 +13,7 @@ def instance_values #:nodoc:
     Hash[instance_variables.map { |name| [name[1..-1], instance_variable_get(name)] }]
   end
 
-  # Returns an array of instance variable names including "@". They are strings
-  # both in Ruby 1.8 and 1.9.
+  # Returns an array of instance variable names including "@". They are strings.
   #
   #   class C
   #     def initialize(x, y)