Bring back initPolymer, allow boot.js only if using "polymer_experimental.html".

pkg/polymer/test/publish_inherited_properties_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.
 
 import 'dart:html';
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'package:polymer/polymer.dart';
 
 // Dart note: unlike JS, you can't publish something that doesn't
@@ skipping 28 matching lines @@
 
 @CustomTag('x-squid')
 class XSquid extends XZot {
   XSquid.created() : super.created();
 
   @published int baz = 13;
   @published int zot = 5;
   @published int squid = 7;
 }
 
-@initMethod
-main() {
+main() => initPolymer().run(() {
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady.then((_) {
     Polymer.register('x-noscript', XZot);
   }));
 
   test('published properties', () {
     published(tag) => (new Element.tag(tag) as PolymerElement)
         .declaration.publishedProperties;
 
     expect(published('x-zot'), ['Foo', 'Bar', 'zot', 'm']);
     expect(published('x-squid'), ['Foo', 'Bar', 'zot', 'm', 'baz', 'squid']);
     expect(published('x-noscript'), ['Foo', 'Bar', 'zot', 'm']);
     // TODO(sigmund): uncomment, see above
     // expect(published('x-squid'), [#Foo, #Bar, #zot, #zap, #baz, #squid]);
   });
-}
+});