[es6] Implement Date.prototype[@@toPrimitive] as C++ builtin.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index aa2e9c0744bd696a9fbbe24685f7d865404a8d47..7acffc9e1e9937aab1083951703abdac7e79a639 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -1461,18 +1461,6 @@ RUNTIME_FUNCTION(Runtime_ToPrimitive_String) {
 }
 
 
-RUNTIME_FUNCTION(Runtime_OrdinaryToPrimitive) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(2, args.length());
-  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, receiver, 0);
-  CONVERT_ARG_HANDLE_CHECKED(String, hint, 1);
-  Handle<Object> result;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, result, JSReceiver::OrdinaryToPrimitive(receiver, hint));
-  return *result;
-}
-
-
 RUNTIME_FUNCTION(Runtime_ToNumber) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());