Clean up directory listing interface.

runtime/bin/directory.h

 // 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.
 
 #ifndef BIN_DIRECTORY_H_
 #define BIN_DIRECTORY_H_
 
 #include "bin/builtin.h"
 #include "bin/globals.h"
 
 class Directory {
  public:
-  static bool Open(const char* path, intptr_t* dir);
-  static bool Close(intptr_t dir);
   static void List(const char* path,
-                   intptr_t dir,
                    bool recursive,
-                   Dart_Port dir_handler,
-                   Dart_Port file_handler,
-                   Dart_Port done_handler,
-                   Dart_Port dir_error_handler);
+                   Dart_Port dir_port,
+                   Dart_Port file_port,
+                   Dart_Port done_port,
+                   Dart_Port error_port);
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Directory);
 };
 
 #endif  // BIN_DIRECTORY_H_