Add test that makes sure print deals with broken toStrings.

tests/corelib/print_test.dart

 // Copyright (c) 2013, 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.
 
-import 'dart:mirrors';
-
 import 'package:expect/expect.dart';
 
-class Foo {
+class A {
+  toString() {
+    if (false
+          || true  /// 01: runtime error
+        ) {
+      return 499;
+    } else {
+      return "ok";
+    }
+  }
 }
 
 main() {
-  Expect.stringEquals('Foo', '${new Foo().runtimeType}');
-  Expect.stringEquals('foo', MirrorSystem.getName(new Symbol('foo')));
+  print(new A());
 }