Ignore all trailing separators in path.extension.

pkg/path/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 builder = new path.Builder(style: path.Style.url,
       root: 'http://dartlang.org/root/path');
 
   test('separator', () {
     expect(builder.separator, '/');
   });
 
   test('extension', () {
     expect(builder.extension(''), '');
     expect(builder.extension('foo.dart'), '.dart');
     expect(builder.extension('foo.dart.js'), '.js');
     expect(builder.extension('a.b/c'), '');
     expect(builder.extension('a.b/c.d'), '.d');
     expect(builder.extension(r'a.b\c'), r'.b\c');
+    expect(builder.extension('foo.dart/'), '.dart');
+    expect(builder.extension('foo.dart//'), '.dart');
   });
 
   test('rootPrefix', () {
     expect(builder.rootPrefix(''), '');
     expect(builder.rootPrefix('a'), '');
     expect(builder.rootPrefix('a/b'), '');
     expect(builder.rootPrefix('http://dartlang.org/a/c'),
         'http://dartlang.org');
     expect(builder.rootPrefix('file:///a/c'), 'file://');
     expect(builder.rootPrefix('/a/c'), '/');
@@ skipping 650 matching lines @@
         Uri.parse('http://dartlang.org/path/to/foo'));
     expect(builder.toUri('http://dartlang.org/path/to/foo/'),
         Uri.parse('http://dartlang.org/path/to/foo/'));
     expect(builder.toUri('file:///path/to/foo'),
         Uri.parse('file:///path/to/foo'));
     expect(builder.toUri('foo/bar'), Uri.parse('foo/bar'));
     expect(builder.toUri('http://dartlang.org/path/to/foo%23bar'),
         Uri.parse('http://dartlang.org/path/to/foo%23bar'));
   });
 }