dart:io | Add File.rename

sdk/lib/io/file.dart

Index: sdk/lib/io/file.dart
diff --git a/sdk/lib/io/file.dart b/sdk/lib/io/file.dart
index ac1a268077f39856bc314f7d6f4e4f0d4cb7e9a6..450a9020abb0920d6203897039b5173815366477 100644
--- a/sdk/lib/io/file.dart
+++ b/sdk/lib/io/file.dart
@@ -80,6 +80,26 @@ abstract class File implements FileSystemEntity {
   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);
+
+   /**
+   * Synchronously renames this file. Returns 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 an exception is thrown.
+   */
+  File renameSync(String newPath);
+
+  /**
    * Get a [Directory] object for the directory containing this
    * file.
    */