Fix crash for type variables with dynamic bound.

tests/language/regress_19728_test.dart

Index: tests/language/regress_19728_test.dart
diff --git a/samples/pop_pop_win/web/game_web.dart b/tests/language/regress_19728_test.dart
similarity index 61%
copy from samples/pop_pop_win/web/game_web.dart
copy to tests/language/regress_19728_test.dart
index fc287491ad5f29284f153db230883217a3e651c2..55dba6cda4c30545a30267bdce23944cb67fb9fb 100644
--- a/samples/pop_pop_win/web/game_web.dart
+++ b/tests/language/regress_19728_test.dart
@@ -1,11 +1,18 @@
 // 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.
-library pop_pop_win.game_web;
 
-import 'platform_web.dart';
-import 'package:pop_pop_win/pop_pop_win.dart';
+// Regression test for issue 19728.
 
-void main() {
-  startGame(new PlatformWeb());
+class C<T extends dynamic> {
+  T field;
+
+  test() {
+    field = 0;
+    int i = field;
+  }
 }
+
+void main() {
+  new C().test();
+}