Fix warnings_checker.dart handling of multitests

tests/language_strong/type_check_const_function_typedef2_test.dart

 // Copyright (c) 2014, 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.
 
 // Tests that typechecks on const objects with typedefs work.
 
 import "package:expect/expect.dart";
 
 typedef String Int2String(int x);
 
 class A {
   final Int2String f;
   const A(this.f);
 }
 
-int // /// 00: static type warning, checked mode compile-time error
+int // //# 00: static type warning, checked mode compile-time error
 foo(
-String // /// 00: continued
+String // //# 00: continued
 x) => 499;
 
 const a = const A(foo);
 
 main() {
   Expect.equals(499, a.f(499));
 }