Implement argument definition test in the vm.

runtime/lib/object.cc

Index: runtime/lib/object.cc
===================================================================
--- runtime/lib/object.cc	(revision 11659)
+++ runtime/lib/object.cc	(working copy)
@@ -43,8 +43,7 @@
     function = instance_class.LookupDynamicFunction(function_name);
   }
   if (!function.IsNull()) {
-    const int total_num_parameters =
-        function.num_fixed_parameters() + function.num_optional_parameters();
+    const int total_num_parameters = function.NumberOfParameters();
     const Array& array = Array::Handle(Array::New(total_num_parameters - 1));
     // Skip receiver.
     for (int i = 1; i < total_num_parameters; i++) {