Fix warnings in analyzer_experimental

pkg/analyzer_experimental/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 'package:args/args.dart';
 import 'package:path/path.dart';
 
 import 'dart:io';
@@ skipping 136 matching lines @@
 
   static _showUsage(parser) {
     print('Usage: $_BINARY_NAME [options...] <libraries to analyze...>');
     print(parser.getUsage());
     print('');
     print('For more information, see http://www.dartlang.org/tools/analyzer.');
   }
 
   static String _getVersion() {
     try {
-      Path versionPath = join(dirname(Platform.script), '..', 'version');;
-      File versionFile = new File.fromPath(versionPath);
+      String versionPath = join(dirname(Platform.script), '..', 'version');;
+      File versionFile = new File(versionPath);
       return versionFile.readAsStringSync().trim();
     } catch (_) {
       // This happens when the script is not running in the context of an SDK.
       return "<unknown>";
     }
   }
 }
 
 /**
  * Commandline argument parser.
@@ skipping 87 matching lines @@
 
   _getNextFlagIndex(args, i) {
     for ( ; i < args.length; ++i) {
       if (args[i].startsWith('--')) {
         return i;
       }
     }
     return i;
   }
 }