Rationalize Dart mojo and sky package structure

mojo/public/dart/internal.dart

Index: mojo/public/dart/internal.dart
diff --git a/mojo/public/dart/internal.dart b/mojo/public/dart/internal.dart
deleted file mode 100644
index 4239df2f6a6c9880a0bb04332d47ebda7b0211b6..0000000000000000000000000000000000000000
--- a/mojo/public/dart/internal.dart
+++ /dev/null
@@ -1,14 +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.
-
-library internal;
-
-import 'dart:async';
-import 'dart:collection';
-import 'dart:isolate';
-import 'dart:typed_data';
-
-part 'src/handle_watcher.dart';
-part 'src/natives.dart';
-part 'src/timer_queue.dart';