Migrate test block 9 to Dart 2.0

tests/corelib_strong/hidden_library2_test.dart

Index: tests/corelib_strong/hidden_library2_test.dart
diff --git a/tests/corelib_strong/hidden_library2_test.dart b/tests/corelib_strong/hidden_library2_test.dart
deleted file mode 100644
index 637cd940779b85b9f1f6a5ceec8f615cdc1811f8..0000000000000000000000000000000000000000
--- a/tests/corelib_strong/hidden_library2_test.dart
+++ /dev/null
@@ -1,15 +0,0 @@
-// 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());
-}