fix relative @HtmlImport paths in deep folders in deployment mode

test/foo/bar.dart

Index: test/foo/bar.dart
diff --git a/lib/web_components.dart b/test/foo/bar.dart
similarity index 62%
copy from lib/web_components.dart
copy to test/foo/bar.dart
index 379d04e689ba1d237e771f21872288f48e43fdc3..67845503e9d6cd6a39ba6ed5499b7239bdb827e5 100644
--- a/lib/web_components.dart
+++ b/test/foo/bar.dart
@@ -1,8 +1,7 @@
 // Copyright (c) 2015, 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 web_components;
+@HtmlImport('bar.html')
+library web_components.test.foo.bar;
 
-export 'src/custom_element.dart';
-export 'custom_element_proxy.dart';
-export 'html_import_annotation.dart';
+import 'package:web_components/web_components.dart';