Fix warnings_checker.dart handling of multitests

tests/language_strong/setter3_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.
 
 // Test that setters cannot have defined, non-void return types.
 // Note: The language specification specifies the absence of a type means
 // it is dynamic, however you cannot specify dynamic.
 
 class A {
   set foo(x) {}
   void set bar(x) {}
-  dynamic set baz(x) {} /// 01: static type warning
-  bool set bob(x) {} /// 02: static type warning
+  dynamic set baz(x) {} //# 01: static type warning
+  bool set bob(x) {} //# 02: static type warning
 }
 
 main() {
   new A();
 }