Object.seal(obj) and Object.freeze(obj) should return the input obj....

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 731 matching lines @@
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("obj_ctor_property_non_object", ["seal"]);
   }
   var names = ObjectGetOwnPropertyNames(obj);
   for (var key in names) {
     var name = names[key];
     var desc = GetOwnProperty(obj, name);
     if (desc.isConfigurable()) desc.setConfigurable(false);
     DefineOwnProperty(obj, name, desc, true);
   }  
-  ObjectPreventExtension(obj);
+  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 key in names) {
     var name = names[key];
     var desc = GetOwnProperty(obj, name);
     if (IsDataDescriptor(desc)) desc.setWritable(false);
     if (desc.isConfigurable()) desc.setConfigurable(false);
     DefineOwnProperty(obj, name, desc, true);
   }  
-  ObjectPreventExtension(obj);
+  return ObjectPreventExtension(obj);
 }
 
 
 // ES5 section 15.2.3.10
 function ObjectPreventExtension(obj) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("obj_ctor_property_non_object", ["preventExtension"]);
   }
   %PreventExtensions(obj);
   return obj;
@@ skipping 399 matching lines @@
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();