dart:io | Add rename to Link

sdk/lib/io/file_impl.dart

Index: sdk/lib/io/file_impl.dart
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index 9ad3001d92fe408b158dd43945837a8ceb1793c7..6d151549f6564130d6a2d7ce7cff2d8881de34fe 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -220,10 +220,11 @@ const int _READ_LIST_REQUEST = 17;
 const int _WRITE_LIST_REQUEST = 18;
 const int _CREATE_LINK_REQUEST = 19;
 const int _DELETE_LINK_REQUEST = 20;
-const int _LINK_TARGET_REQUEST = 21;
-const int _TYPE_REQUEST = 22;
-const int _IDENTICAL_REQUEST = 23;
-const int _STAT_REQUEST = 24;
+const int _RENAME_LINK_REQUEST = 21;
+const int _LINK_TARGET_REQUEST = 22;
+const int _TYPE_REQUEST = 23;
+const int _IDENTICAL_REQUEST = 24;
+const int _STAT_REQUEST = 25;
 
 // TODO(ager): The only reason for this class is that the patching
 // mechanism doesn't seem to like patching a private top level
@@ -334,6 +335,8 @@ class _File implements File {
 
   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 '$_path' to '$newPath'");