Missed clean-up from the last CL

pkg/analyzer_plugin/lib/src/channel/isolate_channel.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:async';
 import 'dart:convert';
 import 'dart:isolate';
 
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer_plugin/channel/channel.dart';
@@ skipping 97 matching lines @@
    * not yet been started by invoking [listen].
    */
   Isolate _isolate;
 
   /**
    * The port used to send requests to the plugin, or `null` if the plugin has
    * not yet been started by invoking [listen].
    */
   SendPort _sendPort;
 
-  ReceivePort receivePort;
+  /**
+   * The port used to receive responses and notifications from the plugin.
+   */
+  ReceivePort _receivePort;
 
-  ReceivePort errorPort;
+  /**
+   * The port used to receive unhandled exceptions thrown in the plugin.
+   */
+  ReceivePort _errorPort;
 
-  ReceivePort exitPort;
+  /**
+   * The port used to receive notification when the plugin isolate has exited.
+   */
+  ReceivePort _exitPort;
 
   /**
    * Initialize a newly created channel to communicate with an isolate running
    * the code at the given [uri].
    */
   ServerIsolateChannel(
       this.pluginUri, this.packagesUri, this.instrumentationService);
   @override
   void close() {
-    receivePort?.close();
-    errorPort?.close();
-    exitPort?.close();
+    _receivePort?.close();
+    _errorPort?.close();
+    _exitPort?.close();
     _isolate = null;
-//    _sendPort = null;
-//    receivePort = null;
-//    errorPort = null;
-//    exitPort = null;
   }
 
   @override
   Future<Null> listen(void onResponse(Response response),
       void onNotification(Notification notification),
       {Function onError, void onDone()}) async {
     if (_isolate != null) {
       throw new StateError('Cannot listen to the same channel more than once.');
     }
-    receivePort = new ReceivePort();
+    _receivePort = new ReceivePort();
     if (onError != null) {
-      errorPort = new ReceivePort();
-      errorPort.listen((error) {
+      _errorPort = new ReceivePort();
+      _errorPort.listen((error) {
         onError(error);
       });
     }
     if (onDone != null) {
-      exitPort = new ReceivePort();
-      exitPort.listen((_) {
+      _exitPort = new ReceivePort();
+      _exitPort.listen((_) {
         onDone();
       });
     }
     _isolate = await Isolate.spawnUri(
-        pluginUri, <String>[], receivePort.sendPort,
-        onError: errorPort?.sendPort,
-        onExit: exitPort?.sendPort,
+        pluginUri, <String>[], _receivePort.sendPort,
+        onError: _errorPort?.sendPort,
+        onExit: _exitPort?.sendPort,
         packageConfig: packagesUri);
     Completer<Null> channelReady = new Completer<Null>();
-    receivePort.listen((dynamic input) {
+    _receivePort.listen((dynamic input) {
       if (input is SendPort) {
 //        print('[server] Received send port');
         _sendPort = input;
         channelReady.complete(null);
       } else if (input is Map) {
         if (input.containsKey('id') != null) {
           String encodedInput = JSON.encode(input);
 //          print('[server] Received response: $encodedInput');
           instrumentationService.logPluginResponse(pluginUri, encodedInput);
           onResponse(new Response.fromJson(input));
@@ skipping 10 matching lines @@
 
   @override
   void sendRequest(Request request) {
     Map<String, Object> json = request.toJson();
     String encodedRequest = JSON.encode(json);
 //    print('[server] Send request: $encodedRequest');
     instrumentationService.logPluginRequest(pluginUri, encodedRequest);
     _sendPort.send(json);
   }
 }