Removed Polymer from Observatory deps

packages/web_components/e2e_test/html_imports/test/basic_test.dart

 // 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.
+@TestOn('browser')
 @HtmlImport('packages/html_imports/theme.html')
 library e2e_test.html_imports.basic_test;
 
 import 'dart:html';
 import 'package:initialize/initialize.dart' as init;
 import 'package:web_components/html_import_annotation.dart';
-import 'package:unittest/html_config.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
-main() {
-  useHtmlConfiguration();
+main() async {
+  // Waits until all html imports are loaded.
+  await init.run();
 
-  // Waits until all html imports are loaded.
-  init.run().then((_) {
-    test('text is red', () {
-      var p = document.createElement('p');
-      document.body.append(p);
-      expect(p.getComputedStyle().color, 'rgb(255, 0, 0)');
-    });
+  test('text is red', () {
+    var p = document.createElement('p');
+    document.body.append(p);
+    expect(p.getComputedStyle().color, 'rgb(255, 0, 0)');
   });
 }