Remove the old task model

pkg/analysis_server/test/analysis/notification_analysis_options_test.dart

 // Copyright (c) 2015, 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 test.analysis.notification.analysis_options;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/services/lint.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
 
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 import '../utils.dart';
 
 main() {
   initializeTestEnvironment();
   defineReflectiveTests(AnalysisOptionsFileNotificationTest);
 }
 
 @reflectiveTest
 class AnalysisOptionsFileNotificationTest extends AbstractAnalysisTest {
-  /// Cached model state in case tests need to set task model to on/off.
-  bool wasTaskModelEnabled;
-
   Map<String, List<AnalysisError>> filesErrors = {};
 
   final testSource = '''
 main() {
   var x = '';
   int y = x; // Not assignable in strong-mode
   print(y);
 }''';
 
   List<AnalysisError> get errors => filesErrors[testFile];
@@ skipping 32 matching lines @@
     addOptionsFile('''
 analyzer:
   strong-mode: $isSet
 ''');
   }
 
   @override
   void setUp() {
     super.setUp();
     server.handlers = [new AnalysisDomainHandler(server)];
-    wasTaskModelEnabled = AnalysisEngine.instance.useTaskModel;
-    AnalysisEngine.instance.useTaskModel = true;
   }
 
   @override
   void tearDown() {
-    AnalysisEngine.instance.useTaskModel = wasTaskModelEnabled;
     filesErrors[optionsFilePath] = [];
     filesErrors[testFile] = [];
     super.tearDown();
   }
 
   test_error_filter() async {
     addOptionsFile('''
 analyzer:
   errors:
     unused_local_variable: ignore
@@ skipping 211 matching lines @@
             AnalysisErrorType.STATIC_TYPE_WARNING,
             AnalysisErrorType.COMPILE_TIME_ERROR
           ]));
     } else {
       // Should only produce a hint.
       expect(errors.map((error) => error.type),
           unorderedEquals([AnalysisErrorType.HINT]));
     }
   }
 }