Add File.copy(Sync) to dart:io.

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 _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 _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 _copy(String oldPath, String newPath) native "File_Copy";
   /* 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 class _RandomAccessFile {
   /* patch */ static int _close(int id) native "File_Close";
   /* patch */ static _readByte(int id) native "File_ReadByte";
@@ skipping 323 matching lines @@
   void _pathWatchedEnd() {
     _subscription.cancel();
     _controller.close();
   }
 }
 
 
 Uint8List _makeUint8ListView(Uint8List source, int offsetInBytes, int length) {
   return new Uint8List.view(source.buffer, offsetInBytes, length);
 }