Rationalize Dart mojo and sky package structure

mojo/public/dart/lib/src/codec.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 bindings;
 
 int align(int size) => size + (kAlignment - (size % kAlignment)) % kAlignment;
 
 const int kAlignment = 8;
 const int kSerializedHandleSize = 4;
@@ skipping 830 matching lines @@
       throw new MojoCodecError(
           'Incorrect header for map. The size is incorrect.');
     }
     if (header.version != kMapStructHeader.version) {
       throw new MojoCodecError(
           'Incorrect header for map. The version is incorrect.');
     }
     return header;
   }
 }