[polymer] switch comment style

pkg/polymer/lib/init.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 that automatically initializes polymer elements without having to
- * write a main for your application.
- *
- * If a polymer application is written entirely with `<polymer-element>` tags
- * and there is no initialization code that needs to happen before these
- * elements are created, then, instead of creating your own `main`, you can
- * simply include a script tag loading this library:
- *
- *    <script type="application/dart">import "package:polymer/init.dart";
- *    </script>
- *
- * This script tag should be placed after all HTML imports on your page.
- */
+/// Library that automatically initializes polymer elements without having to
+/// write a main for your application.
+///
+/// If a polymer application is written entirely with `<polymer-element>` tags
+/// and there is no initialization code that needs to happen before these
+/// elements are created, then, instead of creating your own `main`, you can
+/// simply include a script tag loading this library:
+///
+///    <script type="application/dart">import "package:polymer/init.dart";
+///    </script>
+///
+/// This script tag should be placed after all HTML imports on your page.
 library polymer.init;
 
 import 'package:polymer/polymer.dart';
 
 main() => initPolymer();