Fix warnings_checker.dart handling of multitests

tests/language/default_factory2_test.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.
 
 // Check type bounds when invoking a redirecting factory method
 
 abstract class Foo {}
 
 abstract class IA<T> {
   factory IA() = A<T>;
 }
 
 class A<T extends Foo> implements IA<T> {
    factory A(){}
 }
 
 main() {
-  var result = new IA<String>(); // /// 01: static type warning, dynamic type error
+  var result = new IA<String>(); // //# 01: static type warning, dynamic type error
 }