cleanup unused imports

pkg/analysis_server/lib/src/channel/channel.dart

 // Copyright (c) 2014, 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 channel;
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:analysis_server/src/protocol.dart';
-import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/src/util/utilities_timing.dart';
 
 /**
  * Instances of the class [ChannelChunkSink] uses a [Converter] to translate
  * chunks.
  */
 class ChannelChunkSink<S, T> extends ChunkedConversionSink<S> {
   /**
    * The converter used to translate chunks.
    */
@@ skipping 135 matching lines @@
   /**
    * Send the given [notification] to the client.
    */
   void sendNotification(Notification notification);
 
   /**
    * Send the given [response] to the client.
    */
   void sendResponse(Response response);
 }