Fix warnings_checker.dart handling of multitests

tests/language/get_set_syntax_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.
 
 var get;
-var get a; //           /// 00: compile-time error
-var get b, c; //        /// 01: compile-time error
+var get a; //           //# 00: compile-time error
+var get b, c; //        //# 01: compile-time error
 
 var set;
-var set d; //           /// 02: compile-time error
-var set e, f; //        /// 03: compile-time error
+var set d; //           //# 02: compile-time error
+var set e, f; //        //# 03: compile-time error
 
 class C0 {
   var get;
-  var get a; //         /// 04: compile-time error
-  var get b, c; //      /// 05: compile-time error
+  var get a; //         //# 04: compile-time error
+  var get b, c; //      //# 05: compile-time error
 
   var set;
-  var set d; //         /// 06: compile-time error
-  var set e, f; //      /// 07: compile-time error
+  var set d; //         //# 06: compile-time error
+  var set e, f; //      //# 07: compile-time error
 }
 
 class C1 {
   List get;
   List get a;
-  List get b, c; //     /// 09: compile-time error
+  List get b, c; //     //# 09: compile-time error
 
   List set;
-  List set d; //        /// 10: compile-time error
-  List set e, f; //     /// 11: compile-time error
+  List set d; //        //# 10: compile-time error
+  List set e, f; //     //# 11: compile-time error
 }
 
 class C2 {
   List<int> get;
   List<int> get a;
-  List<int> get b, c; /// 13: compile-time error
+  List<int> get b, c; //# 13: compile-time error
 
   List<int> set;
-  List<int> set d; //   /// 14: compile-time error
-  List<int> set e, f; /// 15: compile-time error
+  List<int> set d; //   //# 14: compile-time error
+  List<int> set e, f; //# 15: compile-time error
 }
 
 main() {
   new C0();
   new C1();
   new C2();
 }