Remove an obsolete flag from test support

pkg/analysis_server/test/stress/utilities/server.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.
 
 /**
  * Support for interacting with an analysis server that is running in a separate
  * process.
  */
 import 'dart:async';
 import 'dart:collection';
@@ skipping 606 matching lines @@
    *
    * If [profileServer] is `true`, the server will be started with "--observe"
    * and "--pause-isolates-on-exit", allowing the observatory to be used.
    *
    * If [useAnalysisHighlight2] is `true`, the server will use the new highlight
    * APIs.
    */
   Future<Null> start(
       {bool checked: true,
       int diagnosticPort,
-      bool enableNewAnalysisDriver: false,
       bool profileServer: false,
       String sdkPath,
       int servicesPort,
       bool useAnalysisHighlight2: false}) async {
     if (_process != null) {
       throw new Exception('Process already started');
     }
     String dartBinary = Platform.executable;
     String rootDir =
         _findRoot(Platform.script.toFilePath(windows: Platform.isWindows));
@@ skipping 32 matching lines @@
     if (diagnosticPort != null) {
       arguments.add('--port');
       arguments.add(diagnosticPort.toString());
     }
     if (sdkPath != null) {
       arguments.add('--sdk=$sdkPath');
     }
     if (useAnalysisHighlight2) {
       arguments.add('--useAnalysisHighlight2');
     }
-    if (!enableNewAnalysisDriver) {
-      arguments.add('--disable-new-analysis-driver');
-    }
 //    stdout.writeln('Launching $serverPath');
 //    stdout.writeln('$dartBinary ${arguments.join(' ')}');
     _process = await Process.start(dartBinary, arguments);
     _process.exitCode.then((int code) {
       if (code != 0) {
         throw new StateError('Server terminated with exit code $code');
       }
     });
     _listenToOutput();
     _serverConnectedCompleter = new Completer();
@@ skipping 385 matching lines @@
     if (buffer.length > 0) {
       buffer.writeln();
       buffer.writeln();
     }
     buffer.writeln(filePath);
     _writeErrors('  Expected ', expectedErrors);
     buffer.writeln();
     _writeErrors('  Found ', actualErrors);
   }
 }