Don't send notifications for disposed contexts.

pkg/analysis_server/lib/src/analysis_server.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 analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:math' show max;
 
@@ skipping 1211 matching lines @@
   void endComputePackageMap() {
     _computingPackageMap(false);
   }
 
   @override
   void removeContext(Folder folder) {
     AnalysisContext context = analysisServer.folderMap.remove(folder);
     if (analysisServer.index != null) {
       analysisServer.index.removeContext(context);
     }
+    analysisServer.operationQueue.contextRemoved(context);
     _onContextsChangedController
         .add(new ContextsChangedEvent(removed: [context]));
     analysisServer.sendContextAnalysisDoneNotifications(
         context, AnalysisDoneReason.CONTEXT_REMOVED);
     context.dispose();
   }
 
   @override
   void updateContextPackageUriResolver(
       Folder contextFolder, UriResolver packageUriResolver) {
@@ skipping 121 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }