Fix a recent regression with nested contexts

pkg/analysis_server/test/analysis_abstract.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.
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
     hide AnalysisOptions;
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 281 matching lines @@
     return null;
   }
 
   @override
   NotificationManager get notificationManager {
     fail('Unexpected invocation of notificationManager');
     return null;
   }
 
   @override
+  List<PluginInfo> get plugins {
+    fail('Unexpected invocation of plugins');
+    return null;
+  }
+
+  @override
   ResourceProvider get resourceProvider {
     fail('Unexpected invocation of resourceProvider');
     return null;
   }
 
   @override
   String get sdkPath {
     fail('Unexpected invocation of sdkPath');
     return null;
   }
@@ skipping 52 matching lines @@
   Future<List<Null>> stopAll() async {
     fail('Unexpected invocation of stopAll');
     return null;
   }
 
   @override
   void whitelistEverything() {
     fail('Unexpected invocation of whitelistEverything');
   }
 }