Make InheritableOptions's constructor more flexible.

activesupport/lib/active_support/configurable.rb

@@ -30,7 +30,7 @@ def config
           superclass.config.inheritable_copy
         else
           # create a new "anonymous" class that will host the compiled reader methods
-          Class.new(Configuration).new({})
+          Class.new(Configuration).new
         end
       end
 

activesupport/lib/active_support/ordered_options.rb

@@ -36,8 +36,12 @@ def method_missing(name, *args)
   end
 
   class InheritableOptions < OrderedOptions
-    def initialize(parent)
-      super() { |h,k| parent[k] }
+    def initialize(parent = nil)
+      if parent
+        super() { |h,k| parent[k] }
+      else
+        super()
+      end
     end
 
     def inheritable_copy