Update charted to 0.4.8 and roll

packages/watcher/test/file_watcher/native_test.dart

 // Copyright (c) 2015, 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.
 
 @TestOn('linux || mac-os')
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:watcher/src/file_watcher/native.dart';
-import 'package:watcher/watcher.dart';
 
 import 'shared.dart';
 import '../utils.dart';
 
 void main() {
   watcherFactory = (file) => new NativeFileWatcher(file);
 
   setUp(() {
     createSandbox();
     writeFile("file.txt");
   });
 
   sharedTests();
 }