dart:io | Add .stat() and .statSync() to FileSystemEntity and subclasses File, Directory, and Link.

sdk/lib/io/directory.dart

Index: sdk/lib/io/directory.dart
diff --git a/sdk/lib/io/directory.dart b/sdk/lib/io/directory.dart
index cd776007a6b280ad3bceedb06c7093bb1fd04798..dfe5637db0ac6247d1e57de90ff84e073c15812f 100644
--- a/sdk/lib/io/directory.dart
+++ b/sdk/lib/io/directory.dart
@@ -7,7 +7,7 @@ part of dart.io;
 /**
  * [Directory] objects are used for working with directories.
  */
-abstract class Directory extends FileSystemEntity {
+abstract class Directory implements FileSystemEntity {
   /**
    * Creates a directory object. The path is either an absolute path,
    * or it is a relative path which is interpreted relative to the directory