Generate dynamic type errors according to spec.

tests/language/src/Prefix23NegativeTest.dart

Index: tests/language/src/Prefix23NegativeTest.dart
===================================================================
--- tests/language/src/Prefix23NegativeTest.dart	(revision 5063)
+++ tests/language/src/Prefix23NegativeTest.dart	(working copy)
@@ -1,17 +0,0 @@
-// Copyright (c) 2012, 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.
-//
-// Unresolved symbols should be reported as an static type warnings.
-// In this variant of test we turn warnings into errors.
-// VMOptions=--enable_type_checks
-
-#library("Prefix22NegativeTest.dart");
-#import("library12.dart", prefix:"lib12");
-
-class myClass {
-  lib12.Library13 fld; /// static type error
-}
-
-main() {
-}