Fix warnings_checker.dart handling of multitests

tests/language/constructor_redirect_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.
 // Dart test program for redirection constructors.
 
 import "package:expect/expect.dart";
 
 class A {
   var x;
   A(this.x) {}
   A.named(x, int y) : this(x + y);
   A.named2(int x, int y, z) : this.named(staticFun(x, y), z);
 
   // The following is a bit tricky. It is a compile-time error to
   // refer to this (implicitly or explicitly) from an initializer.
   // When we remove the line with moreStaticFun, staticFun is really a
   // static function and it is legal to call it. This is what will
   // happen in the /none version of this test. However, in /01,
   // staticFun isn't really a static function and should cause a
   // compile-time error.
   static
-  moreStaticFun() {} /// 01: compile-time error
+  moreStaticFun() {} //# 01: compile-time error
   int staticFun(int v1, int v2) {
     return v1 * v2;
   }
 }
 
 class B extends A {
   B(y) : super(y + 1) {}
   B.named(y) : super.named(y, y + 1) {}
 }
 
@@ skipping 30 matching lines @@
     D d = const D(498);
     Expect.equals(499, d.x);
     d = const D.named(249);
     Expect.equals(499, d.x);
   }
 }
 
 main() {
   ConstructorRedirectTest.testMain();
 }