Some cosmetic issues.

src/array.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 1089 matching lines @@
     "isArray", ArrayIsArray
   ));
 
   var specialFunctions = %SpecialArrayFunctions({});
 
   function getFunction(name, jsBuiltin, len) {
     var f = jsBuiltin;
     if (specialFunctions.hasOwnProperty(name)) {
       f = specialFunctions[name];
     }
-    if (arguments.length == 3) {
+    if (!IS_UNDEFINED(len)) {
       %FunctionSetLength(f, len);
     }
     return f;
   }
 
   // Setup non-enumerable functions of the Array.prototype object and
   // set their names.
   // Manipulate the length of some of the functions to meet
   // expectations set by ECMA-262 or Mozilla.
   InstallFunctionsOnHiddenPrototype($Array.prototype, DONT_ENUM, $Array(
@@ skipping 18 matching lines @@
     "lastIndexOf", getFunction("lastIndexOf", ArrayLastIndexOf, 1),
     "reduce", getFunction("reduce", ArrayReduce, 1),
     "reduceRight", getFunction("reduceRight", ArrayReduceRight, 1)
   ));
     
   %FinishArrayPrototypeSetup($Array.prototype);
 }
 
 
 SetupArray();