Fix warnings_checker.dart handling of multitests

tests/language/const_constructor_super_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.
 
 import "package:expect/expect.dart";
 
 class A {
   final a;
   A(this.a);  // Not const.
   const A.five() : a = 5;
 }
 
 class B extends A {
   final b;
   B(x) : b = x + 1, super(x);
 
   // Const constructor cannot call non-const super constructor.
-  const B.zerofive() : b = 0, super(5); // /// 01: compile-time error
+  const B.zerofive() : b = 0, super(5); // //# 01: compile-time error
 }
 
 class C extends A {
   C() : super(0);
   // Implicit call to non-const constructor A(x).
-  const C.named(x); // /// 02: compile-time error
+  const C.named(x); // //# 02: compile-time error
 }
 
 main() {
-  var b = new B.zerofive(); // /// 01: continued
+  var b = new B.zerofive(); // //# 01: continued
   var b1 = new B(0);
-  var c = new C.named(""); // /// 02: continued
+  var c = new C.named(""); // //# 02: continued
 }