Upgrade V8 to 5.1.281.57

Change-Id: Id981b686b4d587ac31697662eb98bb34be42ad90
diff --git a/test/message/default-parameter-tdz.js b/test/message/default-parameter-tdz.js
index ff2a400..a109196 100644
--- a/test/message/default-parameter-tdz.js
+++ b/test/message/default-parameter-tdz.js
@@ -2,6 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Flags: --harmony-default-parameters
+//
 
 (function(a=+a) { })();