Update charted to 0.4.8 and roll

packages/watcher/lib/src/directory_watcher.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;
-
 import 'dart:io';
 
-import 'watch_event.dart';
 import '../watcher.dart';
 import 'directory_watcher/linux.dart';
 import 'directory_watcher/mac_os.dart';
 import 'directory_watcher/windows.dart';
 import 'directory_watcher/polling.dart';
 
 /// Watches the contents of a directory and emits [WatchEvent]s when something
 /// in the directory has changed.
 abstract class DirectoryWatcher implements Watcher {
   /// The directory whose contents are being monitored.
@@ skipping 12 matching lines @@
   /// watchers.
   factory DirectoryWatcher(String directory, {Duration pollingDelay}) {
     if (FileSystemEntity.isWatchSupported) {
       if (Platform.isLinux) return new LinuxDirectoryWatcher(directory);
       if (Platform.isMacOS) return new MacOSDirectoryWatcher(directory);
       if (Platform.isWindows) return new WindowsDirectoryWatcher(directory);
     }
     return new PollingDirectoryWatcher(directory, pollingDelay: pollingDelay);
   }
 }