Add test case for issue 3147.

tests/standalone/package/packages/package2.dart

Index: tests/standalone/package/packages/package2.dart
===================================================================
--- tests/standalone/package/packages/package2.dart	(revision 0)
+++ tests/standalone/package/packages/package2.dart	(revision 0)
@@ -0,0 +1,10 @@
+// Copyright (c) 2012, 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.
+
+#library("package2");
+
+class X {
+  const X();
+}
+final X x = const X();