Fix missing top frame in exception stacks in product mode

tests/language/stack_trace_test.dart

 // Copyright (c) 2011, 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 program for testing throw statement
 
 import "package:expect/expect.dart";
 
 class MyException {
   const MyException(String message) : message_ = message;
   final String message_;
@@ skipping 103 matching lines @@
 
   d() {
     c();
   }
 
   testBoth() {
     for (config = 0; config < 2; config++) {
       try {
         d();
       } catch (e, s) {
+        print(s);
         Expect.isTrue(s.toString().contains("issue12940"));
       }
     }
   }
 
   static testMain() {
     var test = new RethrowStacktraceTest();
     test.testBoth();
   }
 }
 
 
 main() {
   StackTraceTest.testMain();
   RethrowStacktraceTest.testMain();
 }