Turn on the new task model by default in analysis server.

pkg/analysis_server/test/integration/integration_tests.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 test.integration.analysis;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 579 matching lines @@
   /**
    * Start the server.  If [debugServer] is `true`, the server will be started
    * with "--debug", allowing a debugger to be attached. If [profileServer] is
    * `true`, the server will be started with "--observe" and
    * "--pause-isolates-on-exit", allowing the observatory to be used.
    */
   Future start(
       {bool debugServer: false,
       int diagnosticPort,
       bool profileServer: false,
-      bool newTaskModel: false,
+      bool newTaskModel: true,
       bool useAnalysisHighlight2: false}) {
     if (_process != null) {
       throw new Exception('Process already started');
     }
     _time.start();
     String dartBinary = Platform.executable;
     String rootDir =
         findRoot(Platform.script.toFilePath(windows: Platform.isWindows));
     String serverPath = normalize(join(rootDir, 'bin', 'server.dart'));
     List<String> arguments = [];
     if (debugServer) {
       arguments.add('--debug');
     }
     if (profileServer) {
       arguments.add('--observe');
       arguments.add('--pause-isolates-on-exit');
     }
     if (Platform.packageRoot.isNotEmpty) {
       arguments.add('--package-root=${Platform.packageRoot}');
     }
     arguments.add('--checked');
     arguments.add(serverPath);
     if (diagnosticPort != null) {
       arguments.add('--port');
       arguments.add(diagnosticPort.toString());
     }
     if (useAnalysisHighlight2) {
       arguments.add('--useAnalysisHighlight2');
     }
-    if (newTaskModel) {
-      arguments.add('--${analysisServer.Driver.ENABLE_NEW_TASK_MODEL}');
+    if (!newTaskModel) {
+      arguments.add('--${analysisServer.Driver.DISABLE_NEW_TASK_MODEL}');
     }
     print('Launching $serverPath');
     print('$dartBinary ${arguments.join(' ')}');
     return Process.start(dartBinary, arguments).then((Process process) {
       _process = process;
       process.exitCode.then((int code) {
         _recordStdio('TERMINATED WITH EXIT CODE $code');
         if (code != 0) {
           _badDataFromServer();
         }
@@ skipping 246 matching lines @@
   void populateMismatches(item, List<MismatchDescriber> mismatches);
 
   /**
    * Create a [MismatchDescriber] describing a mismatch with a simple string.
    */
   MismatchDescriber simpleDescription(String description) =>
       (Description mismatchDescription) {
         mismatchDescription.add(description);
       };
 }