Fix VERBOSE_FLUTTER_COMPLETIONS flag.

pkg/analysis_server/lib/src/server/driver.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 driver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 543 matching lines @@
         negatable: false);
     parser.addOption(INSTRUMENTATION_LOG_FILE,
         help:
             "the path of the file to which instrumentation data will be written");
     parser.addFlag(INTERNAL_PRINT_TO_CONSOLE,
         help: "enable sending `print` output to the console",
         defaultsTo: false,
         negatable: false);
     parser.addOption(NEW_ANALYSIS_DRIVER_LOG,
         help: "set a destination for the new analysis driver's log");
-    parser.addOption(VERBOSE_FLUTTER_COMPLETIONS,
+    parser.addFlag(VERBOSE_FLUTTER_COMPLETIONS,
         help: "enable verbose code completion for Flutter (experimental)");
     parser.addOption(PORT_OPTION,
         help: "the http diagnostic port on which the server provides"
             " status and performance information");
     parser.addOption(INTERNAL_DELAY_FREQUENCY);
     parser.addOption(SDK_OPTION, help: "[path] the path to the sdk");
     parser.addFlag(NO_INDEX,
         help: "disable indexing sources", defaultsTo: false, negatable: false);
     parser.addFlag(USE_ANALYSIS_HIGHLIGHT2,
         help: "enable version 2 of semantic highlight",
@@ skipping 90 matching lines @@
 
   _DiagnosticServerImpl();
 
   @override
   Future<int> getServerPort() => httpServer.serveHttp();
 
   Future startOnPort(int port) {
     return httpServer.serveHttp(port);
   }
 }