add verbose option to show hidden args

pkg/dev_compiler/lib/src/analyzer/context.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.
 
 import 'package:args/args.dart' show ArgParser, ArgResults;
 import 'package:analyzer/file_system/file_system.dart'
     show ResourceProvider, ResourceUriResolver;
 import 'package:analyzer/file_system/physical_file_system.dart'
     show PhysicalResourceProvider;
 import 'package:analyzer/source/custom_resolver.dart';
@@ skipping 56 matching lines @@
 
     return new AnalyzerOptions(
         summaryPaths: args['summary'] as List<String>,
         dartSdkPath: sdkPath,
         dartSdkSummaryPath: sdkSummaryPath,
         customUrlMappings: _parseUrlMappings(args['url-mapping']),
         packageRoot: args['package-root'],
         declaredVariables: declaredVariables);
   }
 
-  static void addArguments(ArgParser parser) {
+  static void addArguments(ArgParser parser, {bool hide: true}) {
     parser
       ..addOption('summary',
           abbr: 's', help: 'summary file(s) to include', allowMultiple: true)
       ..addOption('dart-sdk',
-          help: 'Dart SDK Path', defaultsTo: null, hide: true)
+          help: 'Dart SDK Path', defaultsTo: null, hide: hide)
       ..addOption('dart-sdk-summary',
-          help: 'Dart SDK Summary Path', defaultsTo: null, hide: true)
+          help: 'Dart SDK Summary Path', defaultsTo: null, hide: hide)
       ..addOption('package-root',
           abbr: 'p', help: 'Package root to resolve "package:" imports')
       ..addOption('url-mapping',
           help: '--url-mapping=libraryUri,/path/to/library.dart uses\n'
               'library.dart as the source for an import of of "libraryUri".',
           allowMultiple: true,
           splitCommas: false);
   }
 
   static Map<String, String> _parseUrlMappings(Iterable argument) {
@@ skipping 95 matching lines @@
       // The format for defined variables is:
       //     -D<name>=<value>
       var parts = arg.substring(2).split('=');
       declaredVars[parts[0]] = parts.length > 1 ? parts[1] : '';
     } else {
       remainingArgs.add(arg);
     }
   }
   return remainingArgs;
 }