Add server-side communications channel

pkg/analyzer_plugin/lib/src/driver.dart

 // Copyright (c) 2017, 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:isolate';
 
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/src/channel/isolate_channel.dart';
 import 'package:analyzer_plugin/starter.dart';
 
 /**
  * The [Driver] class represents a single running instance of an analysis
  * server plugin. It is responsible for handling the communications with the
  * server and forwarding requests on to the plugin.
  */
 class Driver implements ServerPluginStarter {
   /**
    * The plugin that will be started.
    */
   final ServerPlugin plugin;
 
   /**
    * Initialize a newly created driver that can be used to start the given
    * plugin.
    */
   Driver(this.plugin);
 
   @override
   void start(SendPort sendPort) {
-    IsolateChannel channel = new IsolateChannel(sendPort);
+    PluginIsolateChannel channel = new PluginIsolateChannel(sendPort);
     plugin.start(channel);
   }
 }