Migrate test block 9 to Dart 2.0

tests/corelib_2/hidden_library2_test.dart

 // Copyright (c) 2013, 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.
 
 // Test that the internal hidden library doesn't make problems with taking
 // stack-traces.
 
 main() {
   print(['x'].where((_) {
     // We actually don't really care for the successful case. We just want to
     // make sure that the test doesn't crash when it is negative.
     throw 'fisk'; // //# 01: runtime error
     return true;
   }).toList());
 }