Fix stack_trace tests on Windows.

pkg/stack_trace/test/frame_test.dart

 // Copyright (c) 2013, 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 frame_test;
 
 import 'package:path/path.dart' as path;
 import 'package:stack_trace/stack_trace.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 485 matching lines @@
     test('returns the URI string for non-file URIs', () {
       expect(new Frame.parseVM('#0 Foo (dart:async/future.dart:0:0)').library,
           equals('dart:async/future.dart'));
       expect(new Frame.parseVM('#0 Foo '
               '(http://dartlang.org/stuff/thing.dart:0:0)').library,
           equals('http://dartlang.org/stuff/thing.dart'));
     });
 
     test('returns the relative path for file URIs', () {
       expect(new Frame.parseVM('#0 Foo (foo/bar.dart:0:0)').library,
-          equals('foo/bar.dart'));
+          equals(path.join('foo', 'bar.dart')));
     });
   });
 
   group('.location', () {
     test('returns the library and line/column numbers for non-core '
         'libraries', () {
       expect(new Frame.parseVM('#0 Foo '
               '(http://dartlang.org/thing.dart:5:10)').location,
           equals('http://dartlang.org/thing.dart 5:10'));
       expect(new Frame.parseVM('#0 Foo (foo/bar.dart:1:2)').location,
-          equals('foo/bar.dart 1:2'));
+          equals('${path.join('foo', 'bar.dart')} 1:2'));
     });
   });
 
   group('.package', () {
     test('returns null for non-package URIs', () {
       expect(new Frame.parseVM('#0 Foo (dart:async/future.dart:0:0)').package,
           isNull);
       expect(new Frame.parseVM('#0 Foo '
               '(http://dartlang.org/stuff/thing.dart:0:0)').package,
           isNull);
@@ skipping 26 matching lines @@
           equals('dart:core/uri.dart 5 in Foo'));
     });
 
     test('prints relative paths as relative', () {
       var relative = path.normalize('relative/path/to/foo.dart');
       expect(new Frame.parseFriendly('$relative 5:10  Foo').toString(),
           equals('$relative 5:10 in Foo'));
     });
   });
 }