Upgrade V8 to 5.1.281.57

Change-Id: Id981b686b4d587ac31697662eb98bb34be42ad90
diff --git a/test/message/destructuring-modify-const.js b/test/message/destructuring-modify-const.js
index 88bda35..5575ae9 100644
--- a/test/message/destructuring-modify-const.js
+++ b/test/message/destructuring-modify-const.js
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-destructuring-bind
+//
 'use strict';
 
 const { x : x, y : y } = { x : 1, y : 2 };