Lock the prototype of internal classes.

src/uri.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 374 matching lines @@
 
 // ECMA-262 - B.2.2.
 function URIUnescape(str) {
   var s = ToString(str);
   return %URIUnescape(s);
 }
 
 
 // -------------------------------------------------------------------
 
-function SetupURI() {
-  // Setup non-enumerable URI functions on the global object and set
+function SetUpUri() {
+  %CheckIsBootstrapping();
+  // Set up non-enumerable URI functions on the global object and set
   // their names.
   InstallFunctions(global, DONT_ENUM, $Array(
     "escape", URIEscape,
     "unescape", URIUnescape,
     "decodeURI", URIDecode,
     "decodeURIComponent", URIDecodeComponent,
     "encodeURI", URIEncode,
     "encodeURIComponent", URIEncodeComponent
   ));
 }
 
-SetupURI();
+SetUpUri();