Fix bogus Object.isSealed check in some Array builtins.

src/array.js

 // Copyright 2012 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 445 matching lines @@
   return new_length;
 }
 
 // Appends the arguments to the end of the array and returns the new
 // length of the array. See ECMA-262, section 15.4.4.7.
 function ArrayPush() {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.push");
 
   var n = TO_UINT32(this.length);
   var m = %_ArgumentsLength();
-  if (m > 0 && ObjectIsSealed(this)) {
-    throw MakeTypeError("array_functions_change_sealed",
-                        ["Array.prototype.push"]);
-  }
 
   if (%IsObserved(this))
     return ObservedArrayPush.apply(this, arguments);
 
   for (var i = 0; i < m; i++) {
     this[i+n] = %_Arguments(i);
   }
 
   var new_length = n + m;
   this.length = new_length;
@@ skipping 162 matching lines @@
   return new_length;
 }
 
 function ArrayUnshift(arg1) {  // length == 1
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.unshift");
 
   var len = TO_UINT32(this.length);
   var num_arguments = %_ArgumentsLength();
   var is_sealed = ObjectIsSealed(this);
 
-  if (num_arguments > 0 && is_sealed) {
-    throw MakeTypeError("array_functions_change_sealed",
-                        ["Array.prototype.unshift"]);
-  }
-
   if (%IsObserved(this))
     return ObservedArrayUnshift.apply(this, arguments);
 
   if (IS_ARRAY(this) && !is_sealed) {
     SmartMove(this, 0, 0, len, num_arguments);
   } else {
     if (num_arguments == 0 && ObjectIsFrozen(this)) {
       // In the zero argument case, values from the prototype come into the
       // object. This can't be allowed on frozen arrays.
       for (var i = 0; i < len; i++) {
@@ skipping 974 matching lines @@
   ));
 
   SetUpLockedPrototype(InternalPackedArray, $Array(), $Array(
     "join", getFunction("join", ArrayJoin),
     "pop", getFunction("pop", ArrayPop),
     "push", getFunction("push", ArrayPush)
   ));
 }
 
 SetUpArray();