pkg: analysis aided cleanup

pkg/watcher/test/directory_watcher_test.dart

 // Copyright (c) 2012, 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.
 
-import 'dart:async';
-import 'dart:io';
-
 import 'package:scheduled_test/scheduled_test.dart';
-import 'package:watcher/watcher.dart';
 
 import 'utils.dart';
 
 main() {
   initConfig();
 
   setUp(createSandbox);
 
   test('does not notify for files that already exist when started', () {
     // Make some pre-existing files.
@@ skipping 64 matching lines @@
     writeFile("b.txt", contents: "after");
     expectModifyEvent("b.txt");
   });
 
   test('watches files in subdirectories', () {
     createWatcher();
     writeFile("a/b/c/d/file.txt");
     expectAddEvent("a/b/c/d/file.txt");
   });
 }