Fix deprecation warnings in analyzer and analysis server.

pkg/analyzer/lib/options.dart

 // Copyright (c) 2013, 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 options;
 
 import 'dart:io';
 
 import 'package:args/args.dart';
 
@@ skipping 258 matching lines @@
     _knownFlags.add(name);
     _parser.addOption(name, abbr: abbr, help: help, allowed: allowed,
         allowedHelp: allowedHelp, defaultsTo: defaultsTo, callback: callback,
         allowMultiple: allowMultiple);
   }
 
 
   /**
    * Generates a string displaying usage information for the defined options.
    *
-   * See [ArgParser.getUsage()].
+   * See [ArgParser.usage].
    */
-  String getUsage() => _parser.getUsage();
+  String getUsage() => _parser.usage;
 
   /**
    * Parses [args], a list of command-line arguments, matches them against the
    * flags and options defined by this parser, and returns the result. The
    * values of any defined variables are captured in the given map.
    *
    * See [ArgParser].
    */
   ArgResults parse(List<String> args, Map<String, String> definedVariables) => _parser.parse(_filterUnknowns(parseDefinedVariables(args, definedVariables)));
 
@@ skipping 48 matching lines @@
 
   _getNextFlagIndex(args, i) {
     for ( ; i < args.length; ++i) {
       if (args[i].startsWith('--')) {
         return i;
       }
     }
     return i;
   }
 }