Gets rid of static analysis error in Context2Test

tests/language/src/Context2Test.dart

 // 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.
 // Dart test for capturing.
 
 // Regression test for issue 5991015.
 
 class V {
 
+  notCalled(Function x) { return x(); }
+
   foofoo(x) { return x; }
 
   hoop(input, n) {
     while (n-- > 0) {
       Expect.equals(5, input);
       continue;  // This continue statement must properly unchain the context.
       switch (input) {
         case 3:
           var values = foofoo;
-          readPacked(() => values(input));
+          notCalled(() => values(input));
       }
     }
   }
 }
 
 main() {
   new V().hoop(5, 3);
 }