Fix warnings_checker.dart handling of multitests

tests/language/top_level_getter_no_setter1_test.dart

 // Copyright (c) 2015, 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.
 
 import 'package:expect/expect.dart';
 
 bool getter_visited = false;
 
 int get getter {
   getter_visited = true;
 }
 
 class Class {
   method() {
     try {
-      getter++; /// 01: static type warning
+      getter++; //# 01: static type warning
     } on NoSuchMethodError catch(e) {
-      Expect.isTrue(getter_visited); /// 01: continued
+      Expect.isTrue(getter_visited); //# 01: continued
       return;
     }
-    Expect.fail('Expected NoSuchMethodError'); /// 01: continued
+    Expect.fail('Expected NoSuchMethodError'); //# 01: continued
   }
 }
 
 main() {
   new Class().method();
 }