Fix issue 1447 by not redefining properties unneccesarily in seal and freeze.

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 920 matching lines @@
 
 // ES5 section 15.2.3.8.
 function ObjectSeal(obj) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("obj_ctor_property_non_object", ["seal"]);
   }
   var names = ObjectGetOwnPropertyNames(obj);
   for (var i = 0; i < names.length; i++) {
     var name = names[i];
     var desc = GetOwnProperty(obj, name);
-    if (desc.isConfigurable()) desc.setConfigurable(false);
+    if (!desc.isConfigurable()) continue;
+    desc.setConfigurable(false);

[Lasse Reichstein, 2011/06/10 09:09:10]

Make it 
 if (desc.isConfigurable()) {
   ...
 }
instead of using continue. More readable, since it makes control flow visible by
indentation.

[Mads Ager (chromium), 2011/06/10 09:13:41]

Done.

     DefineOwnProperty(obj, name, desc, true);
   }
   return ObjectPreventExtension(obj);
 }
 
 
 // ES5 section 15.2.3.9.
 function ObjectFreeze(obj) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("obj_ctor_property_non_object", ["freeze"]);
   }
   var names = ObjectGetOwnPropertyNames(obj);
   for (var i = 0; i < names.length; i++) {
     var name = names[i];
     var desc = GetOwnProperty(obj, name);
+    if (!desc.isWritable() && !desc.isConfigurable()) continue;

[Lasse Reichstein, 2011/06/10 09:09:10]

Ditto here: invert the condition and put the rest of the loop inside the if. And
drop the tests before setting Writable and Configurable to false.

[Mads Ager (chromium), 2011/06/10 09:13:41]

Done.

     if (IsDataDescriptor(desc)) desc.setWritable(false);
     if (desc.isConfigurable()) desc.setConfigurable(false);
     DefineOwnProperty(obj, name, desc, true);
   }
   return ObjectPreventExtension(obj);
 }
 
 
 // ES5 section 15.2.3.10
 function ObjectPreventExtension(obj) {
@@ skipping 419 matching lines @@
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();