For batch mode tests, make sure we read stderr in case of a crash.

tests/language/src/BoolTest.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 basic boolean properties.
 // @static-clean
 
 class BoolTest {
   static void testEquality() {
+    int foo = "Hello";
     Expect.equals(true, true);
     Expect.equals(false, false);
     Expect.equals(true, true === true);
     Expect.equals(false, true === false);
     Expect.equals(true, false === false);
     Expect.equals(false, false === true);
     Expect.equals(false, true !== true);
     Expect.equals(true, true !== false);
     Expect.equals(false, false !== false);
     Expect.equals(true, false !== true);
@@ skipping 190 matching lines @@
     testEquality();
     testNegate(true, false);
     testToString();
     testLogicalOp();
   }
 }
 
 main() {
   BoolTest.testMain();
 }