Clean up examples directory

sky/examples/scrolling/scrolling.sky

 <!--
 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 -->
 <import src="/sky/framework/sky-element.sky" />
 <import src="/sky/framework/sky-scrollable.sky" />
 <import src="../data/cities.sky" as="cities" />
 
-<sky-element name="example-scrollable">
+<sky-element>
 <template>
   <style>
   sky-scrollable {
     margin: 20px;
     height: 400px;
     border: 2px solid blue;
   }
   </style>
   <sky-scrollable />
 </template>
 <script>
 import "dart:sky";
 
-@Tagname('example-scrollable')
-class ExampleScrollable extends SkyElement {
+@Tagname('scrolling')
+class Scrolling extends SkyElement {
   void shadowRootReady() {
     Element parent = shadowRoot.querySelector('sky-scrollable');
     for (Map city in cities.kData.getRange(0, 300)) {
       Element div = document.createElement('div');
       div.setChild(new Text(city['name']));
       parent.appendChild(div);
     }
   }
 }
 
-_init(script) => register(script, ExampleScrollable);
+_init(script) => register(script, Scrolling);
 </script>
 </sky-element>