Fix warnings_checker.dart handling of multitests

tests/lib/mirrors/static_metatarget_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.
 
 // Regression test for the combined use of metatargets and static fields with
 // annotations.
 
 @MirrorsUsed(metaTargets:const [Reflectable])
 import 'dart:mirrors';
 
 class A {
-  @reflectable var reflectableField = 0; /// 01: ok
+  @reflectable var reflectableField = 0; //# 01: ok
 
-  @UsedOnlyAsMetadata() var unreflectableField = 1; /// 02: ok
+  @UsedOnlyAsMetadata() var unreflectableField = 1; //# 02: ok
 
-  @reflectable static var reflectableStaticField = 2; /// 03: ok
+  @reflectable static var reflectableStaticField = 2; //# 03: ok
 
   @UsedOnlyAsMetadata() static var unreflectableStaticField = 3;
 }
 
 class Reflectable {
   const Reflectable();
 }
 const Reflectable reflectable = const Reflectable();
 
 class UsedOnlyAsMetadata {
   const UsedOnlyAsMetadata();
 }
 
 void main() {
   print(new A());
 }