Revert "Make window.undefined, window.NaN, window.Infinitiy read-only (ES5 section 15.1.1)"

src/v8natives.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 144 matching lines @@
 
   return %_CallFunction(receiver, f);
 }
 
 
 // ----------------------------------------------------------------------------
 
 
 function SetupGlobal() {
   // ECMA 262 - 15.1.1.1.
-  %SetProperty(global, "NaN", $NaN, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "NaN", $NaN, DONT_ENUM | DONT_DELETE);
 
   // ECMA-262 - 15.1.1.2.
-  %SetProperty(global, "Infinity", 1/0, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "Infinity", 1/0, DONT_ENUM | DONT_DELETE);
 
   // ECMA-262 - 15.1.1.3.
-  %SetProperty(global, "undefined", void 0, 
-               DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "undefined", void 0, DONT_ENUM | DONT_DELETE);
 
   // Setup non-enumerable function on the global object.
   InstallFunctions(global, DONT_ENUM, $Array(
     "isNaN", GlobalIsNaN,
     "isFinite", GlobalIsFinite,
     "parseInt", GlobalParseInt,
     "parseFloat", GlobalParseFloat,
     "eval", GlobalEval
   ));
 }
@@ skipping 1337 matching lines @@
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();