Fix path.toUri for relative paths.

lib/src/internal_style.dart

 // Copyright (c) 2014, 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 path.internal_style;
 
 import 'context.dart';
 import 'style.dart';
 
 /// The internal interface for the [Style] type.
@@ skipping 39 matching lines @@
 
   /// Returns whether [path] is root-relative.
   ///
   /// If [path] is relative or absolute and not root-relative, returns `false`.
   bool isRootRelative(String path);
 
   /// Returns the path represented by [uri] in this style.
   String pathFromUri(Uri uri);
 
   /// Returns the URI that represents the relative path made of [parts].
-  Uri relativePathToUri(String path) =>
-      new Uri(pathSegments: context.split(path));
+  Uri relativePathToUri(String path) {
+    var segments = context.split(path);
+
+    // Ensure that a trailing slash in the path produces a trailing slash in the
+    // URL.
+    if (isSeparator(path.codeUnitAt(path.length - 1))) segments.add('');
+    return new Uri(pathSegments: segments);
+  }
 
   /// Returns the URI that represents [path], which is assumed to be absolute.
   Uri absolutePathToUri(String path);
 }