Fix warnings_checker.dart handling of multitests

tests/language/constructor10_test.dart

 // Copyright (c) 2014, 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.
 
 // Check that the implicit super call for synthetic constructors are checked.
 
 
 class A {
   final x;
   A(this.x);
 }
 
 class B extends A {
-  /* // /// 00: compile-time error
+  /* // //# 00: compile-time error
   B() : super(null);
-  */ // /// 00: continued
+  */ // //# 00: continued
 }
 
 // ==========
 
 class Y extends A {
-  /* // /// 01: compile-time error
+  /* // //# 01: compile-time error
   Y() : super(null);
-  */ // /// 01: continued
+  */ // //# 01: continued
 }
 
 class Z extends Y {
   Z() : super();
 }
 
 // ==============
 
 class G extends A {
-  /* // /// 02: compile-time error
+  /* // //# 02: compile-time error
   G() : super(null);
-  */ // /// 02: continued
+  */ // //# 02: continued
 }
 
 class H extends G {
 }
 
 main() {
   new B().x;
   new Z().x;
   new H().x;
 }