Fix %GetArrayKeys to not skip non-enumerable indices

test/mjsunit/array-shift.js

Index: test/mjsunit/array-shift.js
diff --git a/test/mjsunit/array-shift.js b/test/mjsunit/array-shift.js
index 3601cbbb89aab226e5c090711aeff4a78a84bb4b..ad742e12ee18ca044da7f11be9f7cae82d6fde9b 100644
--- a/test/mjsunit/array-shift.js
+++ b/test/mjsunit/array-shift.js
@@ -106,3 +106,17 @@
   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);
+})();