Add a test for http://code.google.com/p/dart/issues/detail?id=223.

tests/language/src/FactoryArrowTest.dart

Index: tests/language/src/FactoryArrowTest.dart
===================================================================
--- tests/language/src/FactoryArrowTest.dart	(revision 0)
+++ tests/language/src/FactoryArrowTest.dart	(revision 0)
@@ -0,0 +1,12 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class A {
+  A.foo() {}
+  factory A() => new A.foo();
+}
+
+main() {
+  Expect.isTrue(new A() is A);
+}