Remove deprecated string features.

utils/pub/hosted_source.dart

 // Copyright (c) 2012, 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 hosted_source;
 
 import 'dart:async';
 import 'dart:io' as io;
 import 'dart:json' as json;
 import 'dart:uri';
@@ skipping 79 matching lines @@
   }
 
   /// The system cache directory for the hosted source contains subdirectories
   /// for each separate repository URL that's used on the system. Each of these
   /// subdirectories then contains a subdirectory for each package installed
   /// from that site.
   Future<String> systemCacheDirectory(PackageId id) {
     var parsed = _parseDescription(id.description);
     var url = parsed.last.replaceAll(new RegExp(r"^https?://"), "");
     var urlDir = replace(url, new RegExp(r'[<>:"\\/|?*%]'), (match) {
-      return '%${match[0].charCodeAt(0)}';
+      return '%${match[0].codeUnitAt(0)}';
     });
 
     return new Future.immediate(
         path.join(systemCacheRoot, urlDir, "${parsed.first}-${id.version}"));
   }
 
   String packageName(description) => _parseDescription(description).first;
 
   bool descriptionsEqual(description1, description2) =>
       _parseDescription(description1) == _parseDescription(description2);
@@ skipping 50 matching lines @@
 
     var name = description["name"];
     if (name is! String) {
       throw new FormatException("The 'name' key must have a string value.");
     }
 
     var url = description.containsKey("url") ? description["url"] : defaultUrl;
     return new Pair<String, String>(name, url);
   }
 }