Rationalize Dart mojo and sky package structure

mojo/dart/apptest/lib/apptest.dart

 // 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.
 
 library apptest;
 
 import 'dart:async';
 
-import 'package:mojo/public/dart/application.dart';
-import 'package:mojo/public/dart/bindings.dart';
-import 'package:mojo/public/dart/core.dart';
+import 'package:mojo/application.dart';
+import 'package:mojo/bindings.dart';
+import 'package:mojo/core.dart';
 
 // Import and reexport the unittest package. We are a *.dartzip file designed to
 // be linked into your_apptest.mojo file and are your main entrypoint.
 import 'package:unittest/unittest.dart';
 export 'package:unittest/unittest.dart';
 
 // This class is an application that does nothing but tears down the connections
 // between each test.
 class _ConnectionToShellApplication extends Application {
   final List<Function> _testFunctions;
@@ skipping 38 matching lines @@
 //
 // In a dart mojo application, |incoming_handle| is args[0]. |testFunction| is a
 // list of functions that actually contains your testing code, and will pass
 // back an application to each of them.
 runAppTests(var incomingHandle, List<Function> testFunction) {
   var appHandle = new MojoHandle(incomingHandle);
   var application =
       new _ConnectionToShellApplication.fromHandle(appHandle, testFunction);
   unittestConfiguration = new _CleanShutdownConfiguration(application);
 }