Implement recursive directory deletion.

runtime/bin/directory.dart

 // 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.
 
 /**
  * [Directory] objects are used for working with directories.
  */
 interface Directory default _Directory {
   /**
    * Creates a directory object. The path is either a full path or
@@ skipping 47 matching lines @@
    * If the path is the empty string, a default system temp directory and name
    * are used for the template.
    * The path is modified to be the path of the new directory.
    */
   void createTempSync();
 
   /**
    * Deletes the directory with this name. If the operation completes
    * successfully the [deleteHandler] is called. Otherwise the
    * [errorHandler] is called.
+   *
+   * If [recursive] is [:true:] this directory and all sub-directories
+   * and files in the directory are deleted. If [recursive] is
+   * [:false:] only this directory (which must be empty) is
+   * deleted. [recursive] is [:false:] by default.
    */
-  void delete();
+  void delete([bool recursive]);
 
   /**
    * Deletes the directory with this name. Throws an exception
-   * if the directory is not empty or if deletion failed.
+   * if the directory cannot be deleted.
+   *
+   * If [recursive] is [:true:] this directory and all sub-directories
+   * and files in the directory are deleted. If [recursive] is
+   * [:false:] only this directory (which must be empty) is
+   * deleted. [recursive] is [:false:] by default.
    */
-  void deleteSync();
+  void deleteSync([bool recursive]);
 
   /**
    * List the sub-directories and files of this
    * [Directory]. Optionally recurse into sub-directories. For each
    * file and directory, the file or directory handler is called. When
    * all directories have been listed the done handler is called. If
    * the listing operation is recursive, the error handler is called
    * if a subdirectory cannot be opened for listing.
    */
   void list([bool recursive]);
@@ skipping 54 matching lines @@
   final String path;
 }
 
 
 class DirectoryException {
   const DirectoryException([String this.message, int this.errorCode = 0]);
   String toString() => "DirectoryException: $message";
   final String message;
   final int errorCode;
 }