Implement recursive directory deletion.

runtime/bin/directory.h

 // Copyright (c) 2012, 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 "platform/globals.h"
 
@@ skipping 14 matching lines @@
 
   static ExistsResult Exists(const char* path);
 
   static bool Create(const char* path);
 
   static int CreateTemp(const char* const_template,
                         char** path,
                         char* os_error_message,
                         int os_error_message_len);
 
-  static bool Delete(const char* path);
+  static bool Delete(const char* path, bool recursive);
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Directory);
 };
 
 #endif  // BIN_DIRECTORY_H_