Rationalize Dart mojo and sky package structure

sky/framework/elements/sky-toolbar.sky

Index: sky/framework/elements/sky-toolbar.sky
diff --git a/sky/framework/elements/sky-toolbar.sky b/sky/framework/elements/sky-toolbar.sky
deleted file mode 100644
index 093719d60fa03e7891df961b40dffd7c5c9ece32..0000000000000000000000000000000000000000
--- a/sky/framework/elements/sky-toolbar.sky
+++ /dev/null
@@ -1,33 +0,0 @@
-<!--
-// 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>
-  <style>
-    :host {
-      display: flex;
-      flex-direction: row;
-      align-items: center;
-      height: 56px;
-    }
-  </style>
-  <content />
-</template>
-<script>
-import "dart:sky";
-
-@Tagname('sky-toolbar')
-class SkyToolbar extends SkyElement {
-  void shadowRootReady() {
-    shadow.applyTo(shadowRoot);
-  }
-}
-
-_init(script) => register(script, SkyToolbar);
-</script>
-</sky-element>