Remove the old task model

pkg/analysis_server/test/analysis/update_content_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.updateContent;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/services/index/index.dart';
@@ skipping 89 matching lines @@
     server.updateContent(
         '1', {testFile: new AddContentOverlay('main() { print(2); }')});
     // Perform the next single operation: analysis.
     // It will schedule an indexing operation.
     await server.test_onOperationPerformed;
     // Update the file and remove an overlay.
     resourceProvider.updateFile(testFile, 'main() { print(2); }');
     server.updateContent('2', {testFile: new RemoveContentOverlay()});
     // Validate that at the end the unit was indexed.
     await server.onAnalysisComplete;
-    if (AnalysisEngine.instance.useTaskModel) {
-      verify(server.index.index(anyObject, testUnitMatcher)).times(3);
-    } else {
-      verify(server.index.index(anyObject, testUnitMatcher)).times(2);
-    }
+    verify(server.index.index(anyObject, testUnitMatcher)).times(3);
   }
 
   test_multiple_contexts() async {
     String fooPath = '/project1/foo.dart';
     resourceProvider.newFile(
         fooPath,
         '''
 library foo;
 import '../project2/baz.dart';
 main() { f(); }''');
@@ skipping 145 matching lines @@
 
   @override
   bool matches(arg) {
     return arg is CompilationUnit && arg.element.source.fullName == file;
   }
 }
 
 class _MockIndex extends TypedMock implements Index {
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }