Use GetProperty for getting elements.

src/array.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var $arrayConcat;
 var $arrayPush;
 var $arrayPop;
 var $arrayShift;
 var $arraySlice;
 var $arraySplice;
@@ skipping 285 matching lines @@
         if (key < start_i) {
           var current = array[key];
           if (!IS_UNDEFINED(current) || key in array) {
             new_array[key] = current;
           }
         } else if (key >= start_i + del_count) {
           var current = array[key];
           if (!IS_UNDEFINED(current) || key in array) {
             var new_key = key - del_count + num_additional_args;
             new_array[new_key] = current;
-            if (new_key > 0xffffffff) {
+            if (new_key > 0xfffffffe) {
               big_indices = big_indices || new InternalArray();
               big_indices.push(new_key);
             }
           }
         }
       }
     }
   }
   // Move contents of new_array into this array
   %MoveArrayContents(new_array, array);
@@ skipping 1350 matching lines @@
 
 $arrayConcat = ArrayConcatJS;
 $arrayPush = ArrayPush;
 $arrayPop = ArrayPop;
 $arrayShift = ArrayShift;
 $arraySlice = ArraySlice;
 $arraySplice = ArraySplice;
 $arrayUnshift = ArrayUnshift;
 
 });