Fix path.toUri for relative paths.

test/url_test.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.
 
 import 'package:unittest/unittest.dart';
 import 'package:path/path.dart' as path;
 
 main() {
   var context = new path.Context(
       style: path.Style.url, current: 'http://dartlang.org/root/path');
@@ skipping 703 matching lines @@
       expect(context.fromUri('http://dartlang.org/path/to/foo'),
           'http://dartlang.org/path/to/foo');
     });
   });
 
   test('toUri', () {
     expect(context.toUri('http://dartlang.org/path/to/foo'),
         Uri.parse('http://dartlang.org/path/to/foo'));
     expect(context.toUri('http://dartlang.org/path/to/foo/'),
         Uri.parse('http://dartlang.org/path/to/foo/'));
+    expect(context.toUri('path/to/foo/'), Uri.parse('path/to/foo/'));
     expect(
         context.toUri('file:///path/to/foo'), Uri.parse('file:///path/to/foo'));
     expect(context.toUri('foo/bar'), Uri.parse('foo/bar'));
     expect(context.toUri('http://dartlang.org/path/to/foo%23bar'),
         Uri.parse('http://dartlang.org/path/to/foo%23bar'));
     // Since the input path is also a URI, special characters should already
     // be percent encoded there too.
     expect(context.toUri(r'http://foo.com/_%7B_%7D_%60_%5E_%20_%22_%25_'),
         Uri.parse('http://foo.com/_%7B_%7D_%60_%5E_%20_%22_%25_'));
     expect(context.toUri(r'_%7B_%7D_%60_%5E_%20_%22_%25_'),
@@ skipping 22 matching lines @@
 
     test('with a root-relative URI', () {
       expect(context.prettyUri('/a/b'), '/a/b');
     });
 
     test('with a Uri object', () {
       expect(context.prettyUri(Uri.parse('a/b')), 'a/b');
     });
   });
 }