dart:io | Add FileSystemEntity.parent, make File.directory call it.

sdk/lib/io/file_impl.dart

 // Copyright (c) 2013, 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;
 
 // Read the file in blocks of size 64k.
 const int _BLOCK_SIZE = 64 * 1024;
 
 
@@ skipping 290 matching lines @@
   external static _rename(String oldPath, String newPath);
 
   external static _renameLink(String oldPath, String newPath);
 
   File renameSync(String newPath) {
     var result = _rename(path, newPath);
     throwIfError(result, "Cannot rename file to '$newPath'", path);
     return new File(newPath);
   }
 
-  Directory get directory {
-    _Path path = new _Path(this.path).directoryPath;
-    return new Directory(path.toNativePath());
-  }
+  Directory get directory => super.parent;
 
   Future<RandomAccessFile> open({FileMode mode: FileMode.READ}) {
     if (mode != FileMode.READ &&
         mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
       return new Future.error(new ArgumentError());
     }
     return _IOService.dispatch(_FILE_OPEN, [path, mode._mode]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "Cannot open file", path);
@@ skipping 545 matching lines @@
 
   void _checkAvailable() {
     if (_asyncDispatched) {
       throw new FileException("An async operation is currently pending", path);
     }
     if (closed) {
       throw new FileException("File closed", path);
     }
   }
 }