Rationalize Dart mojo and sky package structure

mojo/public/dart/core.dart

Index: mojo/public/dart/core.dart
diff --git a/mojo/public/dart/core.dart b/mojo/public/dart/core.dart
deleted file mode 100644
index e72da3f211934a0d3718543ae10fab843fe2b5f8..0000000000000000000000000000000000000000
--- a/mojo/public/dart/core.dart
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2014 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 core;
-
-import 'dart:async';
-import 'dart:collection';
-import 'dart:isolate';
-import 'dart:mojo.internal';
-import 'dart:typed_data';
-
-part 'src/buffer.dart';
-part 'src/data_pipe.dart';
-part 'src/drain_data.dart';
-part 'src/event_stream.dart';
-part 'src/handle.dart';
-part 'src/message_pipe.dart';
-part 'src/types.dart';