Move sky-*.sky into framework/elements

sky/framework/elements/sky-toolbar.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="shadow.sky" as="shadow" />
 <import src="sky-element.sky" />
 
 <sky-element attributes="level:number">
 <template>
@@ skipping 12 matching lines @@
 @Tagname('sky-toolbar')
 class SkyToolbar extends SkyElement {
   void shadowRootReady() {
     shadow.applyTo(shadowRoot);
   }
 }
 
 _init(script) => register(script, SkyToolbar);
 </script>
 </sky-element>