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

runtime/bin/file_patch.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.
 
 patch class _FileUtils {
   /* patch */ static SendPort _newServicePort() native "File_NewServicePort";
 }
 
 patch class _File {
   /* patch */ static _exists(String path) native "File_Exists";
   /* patch */ static _create(String path) native "File_Create";
   /* patch */ static _createLink(String path, String target)
       native "File_CreateLink";
   /* patch */ static _linkTarget(String path) native "File_LinkTarget";
-  /* patch */ static _delete(String path) native "File_Delete";
-  /* patch */ static _deleteLink(String path) native "File_DeleteLink";
+  /* patch */ static _deleteNative(String path) native "File_Delete";
+  /* patch */ static _deleteLinkNative(String path) native "File_DeleteLink";
   /* patch */ static _rename(String oldPath, String newPath)
       native "File_Rename";
   /* patch */ static _renameLink(String oldPath, String newPath)
       native "File_RenameLink";
   /* patch */ static _lengthFromPath(String path) native "File_LengthFromPath";
   /* patch */ static _lastModified(String path) native "File_LastModified";
   /* patch */ static _open(String path, int mode) native "File_Open";
   /* patch */ static int _openStdio(int fd) native "File_OpenStdio";
   /* patch */ static _fullPath(String path) native "File_FullPath";
 }
@@ skipping 124 matching lines @@
 
   int _watchPath(String path, int events, bool recursive)
       native "FileSystemWatcher_WatchPath";
   void _unwatchPath() native "FileSystemWatcher_UnwatchPath";
   List _readEvents() native "FileSystemWatcher_ReadEvents";
 }
 
 Uint8List _makeUint8ListView(Uint8List source, int offsetInBytes, int length) {
   return new Uint8List.view(source.buffer, offsetInBytes, length);
 }