Fix warnings_checker.dart handling of multitests

tests/language_strong/symbol_literal_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.
 
 // Test symbol literals.
 
 library symbol_literal_test;
 
 import 'package:expect/expect.dart';
 
@@ skipping 24 matching lines @@
   check(const Symbol("=="), #==);
   check(const Symbol("=="), # ==);
   check(const Symbol("a.toString"), #a.toString);
 
   Expect.equals(1, testSwitch(#abc));
 
   const m = const <Symbol, int>{#A:0, #B:1};
   Expect.equals(1, m[#B]);
 
   // Tries to call the symbol literal #a.toString
-  Expect.throws(() => #a.toString(), (e) => e is NoSuchMethodError); /// 01: static type warning
+  Expect.throws(() => #a.toString(), (e) => e is NoSuchMethodError); //# 01: static type warning
 }