Remove more libraries directives from server

pkg/analysis_server/lib/src/watch_manager.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.
 
-library context.directory.manager;
-
 import 'dart:async';
 import 'dart:collection';
 import 'dart:core';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:watcher/watcher.dart';
 
 /**
  * A function called when a watch [event] associated with a watched resource is
  * received. The list of [tokens] will contain all of the tokens associated with
@@ skipping 261 matching lines @@
   void _removeChild(WatchNode<T> child) {
     _children.remove(child);
     Iterable<WatchNode<T>> grandchildren = child.children;
     for (WatchNode<T> grandchild in grandchildren) {
       grandchild.parent = this;
       _children.add(grandchild);
     }
     child._children.clear();
   }
 }