Adding test for removed ShadowDOM layout test.

tests/html/shadow_dom_test.dart

 // Copyright (c) 2011, 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 ShadowDOMTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 48 matching lines @@
     // work properly. This is blocked on having a good way to do browser
     // rendering tests.
 
     test('Querying in shadowed fragment respects the shadow boundary.', () {
       expect(() {
         init();
 
         expect(shadowRoot.queryAll('.foo'), equals([paragraph1]));
       }, expectation);
     });
+
+    if (ShadowRoot.supported) {
+      test('Shadowroot contents are distributed', () {
+
+        var div = new DivElement();
+
+        var box1 = new DivElement()
+          ..classes.add('foo');
+        div.append(box1);
+
+        var box2 = new DivElement();
+        div.append(box2);
+
+        var sRoot = div.createShadowRoot();
+        var content1 = new ContentElement()
+          ..select = ".foo";
+        sRoot.append(content1);
+
+        var content2 = new ContentElement();
+        sRoot.append(content2);
+
+        expect(content1.getDistributedNodes(), [box1]);
+        expect(content2.getDistributedNodes(), [box2]);
+      });
+    }
   });
 }