fix stringToCodePoints on VM

tests/utils/utf_test.dart

Index: tests/utils/utf_test.dart
diff --git a/tests/utils/utf_test.dart b/tests/utils/utf_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..64417895cefb712ea9c078aa65524297b39380ff
--- /dev/null
+++ b/tests/utils/utf_test.dart
@@ -0,0 +1,14 @@
+// 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 utf_test;
+import 'dart:utf';
+
+main() {
+  String str = codepointsToString([0x1d537]);
+  // String.charCodes gives 16-bit code units, but stringToCodepoints gives
+  // back the original code points.
+  Expect.listEquals([0xd835, 0xdd37], str.charCodes);
+  Expect.listEquals([0x1d537], stringToCodepoints(str));
+}