Update charted to 0.4.8 and roll

packages/watcher/lib/src/directory_watcher/polling.dart

 // Copyright (c) 2013, 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.
 
-library watcher.directory_watcher.polling;
-
 import 'dart:async';
 import 'dart:io';
 
 import '../async_queue.dart';
 import '../directory_watcher.dart';
 import '../resubscribable.dart';
 import '../stat.dart';
 import '../utils.dart';
 import '../watch_event.dart';
 
@@ skipping 156 matching lines @@
 
     if (!isReady) _ready.complete();
 
     // Wait and then poll again.
     return new Future.delayed(_pollingDelay).then((_) {
       if (_events.isClosed) return;
       _poll();
     });
   }
 }