Migrate test block 30 + corelib portion of block 31 to Dart 2.0.

tests/corelib_strong/throw_half_surrogate_pair_test.dart

Index: tests/corelib_strong/throw_half_surrogate_pair_test.dart
diff --git a/tests/corelib_strong/throw_half_surrogate_pair_test.dart b/tests/corelib_strong/throw_half_surrogate_pair_test.dart
deleted file mode 100644
index f500cb1a14331ae2e6a9a8c499ea806a12c6a279..0000000000000000000000000000000000000000
--- a/tests/corelib_strong/throw_half_surrogate_pair_test.dart
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright (c) 2014, 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.
-
-main() {
-  var trebleClef = "\u{1D11E}";
-  if (trebleClef.length != 2) throw "String should be a surrogate pair";
-  // These uncaught exceptions should not cause the VM to crash attempting to
-  // print a malformed string.
-  throw trebleClef[0]; // //# 01: runtime error
-  throw trebleClef[1]; // //# 02: runtime error
-}