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

sdk/lib/io/file.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;
 
 /**
  * FileMode describes the modes in which a file can be opened.
  */
 class FileMode {
@@ skipping 42 matching lines @@
   /**
    * Synchronously create the file. Existing files are left untouched
    * by [createSync]. Calling [createSync] on an existing file might fail
    * if there are restrictive permissions on the file.
    *
    * Throws a [FileException] if the operation fails.
    */
   void createSync();
 
   /**
-   * Delete the file. Returns a [:Future<File>:] that completes with
-   * the file when it has been deleted. Only a file or a link to a file
-   * can be deleted with this method, not a directory or a broken link.
-   */
-  Future<File> delete();
-
-  /**
-   * Synchronously delete the file. Only a file or a link to a file
-   * can be deleted with this method, not a directory or a broken link.
-   *
-   * Throws a [FileException] if the operation fails.
-   */
-  void deleteSync();
-
-  /**
    * Renames this file. Returns a `Future<File>` that completes
    * with a [File] instance for the renamed file.
    *
    * If [newPath] identifies an existing file, that file is
    * replaced. If [newPath] identifies an existing directory, the
    * operation fails and the future completes with an exception.
    */
   Future<File> rename(String newPath);
 
    /**
@@ skipping 452 matching lines @@
       }
     } else if (osError != null) {
       sb.write(": osError");
       if (path != null) {
         sb.write(", path = $path");
       }
     }
     return sb.toString();
   }
 }