Move delete/deleteSync up to FileSystemEntity, with a shared documentation.

sdk/lib/io/directory_impl.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.
 
 part of dart.io;
 
 class _Directory extends FileSystemEntity implements Directory {
   static const CREATE_REQUEST = 0;
   static const DELETE_REQUEST = 1;
   static const EXISTS_REQUEST = 2;
@@ skipping 11 matching lines @@
       throw new ArgumentError('${Error.safeToString(path)} '
                               'is not a String');
     }
   }
 
   external static String _current();
   external static _setCurrent(path);
   external static _createTemp(String template);
   external static int _exists(String path);
   external static _create(String path);
-  external static _delete(String path, bool recursive);
+  external static _deleteNative(String path, bool recursive);
   external static _rename(String path, String newPath);
   external static List _list(String path, bool recursive, bool followLinks);
   external static SendPort _newServicePort();
 
   static Directory get current => new _Directory(_current());
 
   static void set current(path) {
     if (path is Directory) path = path.path;
     var result = _setCurrent(path);
     if (result is ArgumentError) throw result;
@@ skipping 133 matching lines @@
   Directory createTempSync() {
     var result = _createTemp(path);
     if (result is OSError) {
       throw new DirectoryException("Creation of temporary directory failed",
                                    path,
                                    result);
     }
     return new Directory(result);
   }
 
-  Future<Directory> delete({recursive: false}) {
+  Future<Directory> _delete({recursive: false}) {
     _ensureDirectoryService();
     List request = new List(3);
     request[0] = DELETE_REQUEST;
     request[1] = path;
     request[2] = recursive;
     return _directoryService.call(request).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionOrErrorFromResponse(response, "Deletion failed");
       }
       return this;
     });
   }
 
-  void deleteSync({recursive: false}) {
-    var result = _delete(path, recursive);
+  void _deleteSync({recursive: false}) {
+    var result = _deleteNative(path, recursive);
     if (result is OSError) {
       throw new DirectoryException("Deletion failed", path, result);
     }
   }
 
   Future<Directory> rename(String newPath) {
     _ensureDirectoryService();
     List request = new List(3);
     request[0] = RENAME_REQUEST;
     request[1] = path;
@@ skipping 187 matching lines @@
       controller.addError(
           new DirectoryException("Directory listing failed",
                                  errorPath,
                                  err));
     } else {
       controller.addError(
           new DirectoryException("Internal error"));
     }
   }
 }