remove default arguments that aren't used

we always pass all parameters, so there is no reason to provide default
arguments.

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -514,7 +514,7 @@ def empty?
         routes.empty?
       end
 
-      def add_route(app, conditions = {}, requirements = {}, defaults = {}, name = nil, anchor = true)
+      def add_route(app, conditions, requirements, defaults, name, anchor)
         raise ArgumentError, "Invalid route name: '#{name}'" unless name.blank? || name.to_s.match(/^[_a-z]\w*$/i)
 
         if name && named_routes[name]