Remove dart:codec and move classes into dart:convert.

sdk/lib/convert/codec.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library dart.codec;
-
-import 'dart:convert';
-
-part 'encoding.dart';
-part 'json.dart';
+part of dart.convert;
 
 /**
  * A [Codec] encodes and (if supported) decodes data.
  *
  * Codecs can be fused. For example fusing [JSON] and [UTF8] produces
  * an encoder that can convert Json objects directly to bytes, or can decode
  * bytes directly to json objects.
  *
  * Fused codecs generally attempt to optimize the operations and can be faster
  * than executing each step of an encoding separately.
@@ skipping 77 matching lines @@
 class _InvertedCodec<T, S> extends Codec<T, S> {
   final Codec<S, T> _codec;
 
   _InvertedCodec(Codec<S, T> codec) : _codec = codec;
 
   Converter<T, S> get encoder => _codec.decoder;
   Converter<S, T> get decoder => _codec.encoder;
 
   Codec<S, T> get inverted => _codec;
 }