Enable polymorphic inlining of StringBase [] and StringBase codeUnitAt

tests/language/vm/typed_data_polymorphic_view_test.dart

Index: tests/language/vm/typed_data_polymorphic_view_test.dart
diff --git a/tests/language/vm/typed_data_polymorphic_view_test.dart b/tests/language/vm/typed_data_polymorphic_view_test.dart
index 1b94d1099fcbf9d57f19cbb9623f50f5a1f0bd70..94952e2c59461ce15b48753ccebddfd490bbe055 100644
--- a/tests/language/vm/typed_data_polymorphic_view_test.dart
+++ b/tests/language/vm/typed_data_polymorphic_view_test.dart
@@ -1,3 +1,9 @@
+// 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.
+// Tests that the VM does not crash on weird corner cases of class Math.
+// VMOptions=--optimization_counter_threshold=10
+
 import 'dart:typed_data';
 import 'package:expect/expect.dart';