Create a sensible package cache directory on Windows.

utils/pub/io.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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 #library('io');
 
 #import('dart:io');
@@ skipping 351 matching lines @@
   // automatically attach a timeout to that stream.
   uri = _getUri(uri);
 
   var completer = new Completer<InputStream>();
   var client = new HttpClient();
   var connection = client.getUrl(uri);
 
   connection.onError = (e) {
     // Show a friendly error if the URL couldn't be resolved.
     if (e is SocketIOException &&
+        e.osError != null &&
         (e.osError.errorCode == 8 ||
          e.osError.errorCode == -2 ||
          e.osError.errorCode == -5 ||
          e.osError.errorCode == 11004)) {
       e = 'Could not resolve URL "${uri.origin}".';
     }
 
     client.shutdown();
     completer.completeException(e);
   };
@@ skipping 323 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }