Fix warnings_checker.dart handling of multitests

tests/language/redirecting_factory_infinite_steps_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.
 
 // From Dart Language Specification, 0.12 M1, "7.6.2 Factories": It is
 // a compile-time error if a redirecting factory constructor does not
 // redirect to a non-redirecting factory constructor or to a
 // generative constructor in a finite number of steps.
 
 // TODO(ahe): The above specification will probably change to
 // something like: "It is a compile-time error if a redirecting
 // factory constructor redirects to itself, either directly or
 // indirectly via a sequence of redirections."
 
 class Foo extends Bar {
-  factory Foo() = Bar; /// 01: static type warning, dynamic type error
+  factory Foo() = Bar; //# 01: static type warning, dynamic type error
 }
 
 class Bar {
-  factory Bar() = Foo; /// 02: compile-time error
+  factory Bar() = Foo; //# 02: compile-time error
 }
 
 main() {
   new Foo();
 }