dart:io | Add .stat() and .statSync() to FileSystemEntity and subclasses File, Directory, and 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 53a0f504a8872d2ca6ed7c65f6660979ea43676b..b855fef6d4c55157802c599675409965884a4a73 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -266,6 +266,10 @@ class _File implements File {
     return result;
   }
 
+  Future<FileStat> stat() => FileStat.stat(path);
+
+  FileStat statSync() => FileStat.statSync(path);
+
   Future<File> create() {
     _ensureFileService();
     List request = new List(2);