Add Uri.directory constructor.

sdk/lib/io/directory_impl.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.
 
 part of dart.io;
 
 class _Directory extends FileSystemEntity implements Directory {
   final String path;
 
   _Directory(this.path) {
@@ skipping 26 matching lines @@
     if (path is Directory) path = path.path;
     var result = _setCurrent(path);
     if (result is ArgumentError) throw result;
     if (result is OSError) {
       throw new FileSystemException(
           "Setting current working directory failed", path, result);
     }
   }
 
   Uri get uri {
-    String path = this.path;
-    if (!path.endsWith("/")) {
-      path = path + "/";
-    }
-    return new Uri.file(path);
+    return new Uri.directory(path);
   }
 
   Future<bool> exists() {
     return _IOService._dispatch(_DIRECTORY_EXISTS, [path]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionOrErrorFromResponse(response, "Exists failed");
       }
       return response == 1;
     });
   }
@@ skipping 326 matching lines @@
       controller.addError(
           new FileSystemException("Directory listing failed",
                                   errorPath,
                                   err));
     } else {
       controller.addError(
           new FileSystemException("Internal error"));
     }
   }
 }