ES6: Add support for Map and Set Iterator

test/mjsunit/regress/regress-3281.js

Index: test/mjsunit/regress/regress-3281.js
diff --git a/test/mjsunit/regress/regress-3281.js b/test/mjsunit/regress/regress-3281.js
index ebb25991d8510eb1c7441900a0f41cdaac502cf2..ee256b89e2062b184e5ffff14ba370f9afd7a3fb 100644
--- a/test/mjsunit/regress/regress-3281.js
+++ b/test/mjsunit/regress/regress-3281.js
@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony-collections
-
+// Flags: --harmony-collections --expose-natives-as=builtins
 // Should not crash or raise an exception.
 
 var s = new Set();
-var setIterator = %SetCreateIterator(s, 2);
+var setIterator = new builtins.SetIterator(s, 2);
 
 var m = new Map();
-var mapIterator = %MapCreateIterator(m, 2);
+var mapIterator = new builtins.MapIterator(m, 2);