Remove deprecated dart:utf library.

tests/lib/utf/utf_test.dart

Index: tests/lib/utf/utf_test.dart
diff --git a/tests/lib/utf/utf_test.dart b/tests/lib/utf/utf_test.dart
deleted file mode 100644
index 85a856438a0379620842013627a4019da59fd0af..0000000000000000000000000000000000000000
--- a/tests/lib/utf/utf_test.dart
+++ /dev/null
@@ -1,15 +0,0 @@
-// 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 "package:expect/expect.dart";
-import 'dart:utf';
-
-main() {
-  String str = new String.fromCharCodes([0x1d537]);
-  // String.codeUnits gives 16-bit code units, but stringToCodepoints gives
-  // back the original code points.
-  Expect.listEquals([0xd835, 0xdd37], str.codeUnits);
-  Expect.listEquals([0x1d537], stringToCodepoints(str));
-}