Remove an obsolete flag from test support

pkg/analysis_server/test/stress/utilities/server.dart

Index: pkg/analysis_server/test/stress/utilities/server.dart
diff --git a/pkg/analysis_server/test/stress/utilities/server.dart b/pkg/analysis_server/test/stress/utilities/server.dart
index 9e5e051dbcb2489edffbf61a0e2c1d20021bf6f7..c810c7d6fc095cfba53c3b8b3e4b94b40b610a1a 100644
--- a/pkg/analysis_server/test/stress/utilities/server.dart
+++ b/pkg/analysis_server/test/stress/utilities/server.dart
@@ -624,7 +624,6 @@ class Server {
   Future<Null> start(
       {bool checked: true,
       int diagnosticPort,
-      bool enableNewAnalysisDriver: false,
       bool profileServer: false,
       String sdkPath,
       int servicesPort,
@@ -677,9 +676,6 @@ class Server {
     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);