Rationalize Dart mojo and sky package structure

examples/dart/device_info/BUILD.gn

 # 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("//mojo/public/dart/rules.gni")
 
-dart_packaged_application("device_info") {
+dartzip_packaged_application("device_info") {
   output_name = "dart_device_info_example"
   sources = [
     "main.dart",
   ]
   deps = [
     "//mojo/public/dart",
     "//mojo/services/device_info/public/interfaces",
   ]
 }