Fix path.toUri for relative paths.

test/windows_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.
 
 library path.test.windows_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:path/path.dart' as path;
 
 import 'utils.dart';
@@ skipping 611 matching lines @@
     test('with a string', () {
       expect(context.fromUri('file:///C:/path/to/foo'), r'C:\path\to\foo');
     });
   });
 
   test('toUri', () {
     expect(
         context.toUri(r'C:\path\to\foo'), Uri.parse('file:///C:/path/to/foo'));
     expect(context.toUri(r'C:\path\to\foo\'),
         Uri.parse('file:///C:/path/to/foo/'));
+    expect(context.toUri(r'path\to\foo\'), Uri.parse('path/to/foo/'));
     expect(context.toUri(r'C:\'), Uri.parse('file:///C:/'));
     expect(context.toUri(r'\\server\share'), Uri.parse('file://server/share'));
     expect(
         context.toUri(r'\\server\share\'), Uri.parse('file://server/share/'));
     expect(context.toUri(r'foo\bar'), Uri.parse('foo/bar'));
     expect(context.toUri(r'C:\path\to\foo#bar'),
         Uri.parse('file:///C:/path/to/foo%23bar'));
     expect(context.toUri(r'\\server\share\path\to\foo#bar'),
         Uri.parse('file://server/share/path/to/foo%23bar'));
     expect(context.toUri(r'C:\_{_}_`_^_ _"_%_'),
@@ skipping 24 matching lines @@
 
     test('with a root-relative URI', () {
       expect(context.prettyUri('/D:/a/b'), r'D:\a\b');
     });
 
     test('with a Uri object', () {
       expect(context.prettyUri(Uri.parse('a/b')), r'a\b');
     });
   });
 }