Fix %GetArrayKeys to not skip non-enumerable indices

test/mjsunit/array-shift.js

 // Copyright 2010 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 88 matching lines @@
   array_proto[5] = "@5";
   assertEquals(array[5], array_proto[5]);
   assertFalse(array.hasOwnProperty(5));
 
   assertEquals(array[3], array_proto[3]);
   assertFalse(array.hasOwnProperty(3));
 
   assertEquals(array[7], array_proto[7]);
   assertFalse(array.hasOwnProperty(7));
 })();
+
+// Check that non-enumerable elements are treated appropriately
+(function() {
+  var array = [1, 2, 3];
+  Object.defineProperty(array, '1', {enumerable: false});
+  assertEquals(1, array.shift());
+  assertEquals([2, 3], array);
+
+  array = [1,,3];
+  array.__proto__[1] = 2;
+  Object.defineProperty(array.__proto__, '1', {enumerable: false});
+  assertEquals(1, array.shift());
+  assertEquals([2, 3], array);
+})();