Rationalize Dart mojo and sky package structure

mojo/public/dart/lib/src/data_pipe.dart

 // 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.
 
 part of core;
 
 class MojoDataPipeProducer {
   static const int FLAG_NONE = 0;
   static const int FLAG_ALL_OR_NONE = 1 << 0;
 
@@ skipping 147 matching lines @@
     MojoHandle consumerHandle = new MojoHandle(result[2]);
     MojoDataPipe pipe = new MojoDataPipe._internal();
     pipe.producer = new MojoDataPipeProducer(
         producerHandle, new MojoResult(result[0]), elementBytes);
     pipe.consumer = new MojoDataPipeConsumer(
         consumerHandle, new MojoResult(result[0]), elementBytes);
     pipe.status = new MojoResult(result[0]);
     return pipe;
   }
 }