Fix warnings_checker.dart handling of multitests

tests/language/constructor9_test.dart

 // Copyright (c) 2011, 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 that all final instance fields of a class are initialized by
 // constructors.
 
 
 class Klass {
   Klass(var v): field_ = v { }
-  final uninitializedFinalField_; // /// 01: static type warning
+  final uninitializedFinalField_; // //# 01: static type warning
   var field_;
 }
 
 
 main() {
   new Klass(5);
 }