Remove Encoding-enum from dart:io and add interface in dart:convert.

sdk/lib/convert/latin1.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.
 
 part of dart.convert;
 
 /**
  * An instance of the default implementation of the [Latin1Codec].
  *
  * This instance provides a convenient access to the most common ISO Latin 1
  * use cases.
  *
  * Examples:
  *
  *     var encoded = LATIN1.encode("blåbærgrød");
  *     var decoded = LATIN1.decode([0x62, 0x6c, 0xe5, 0x62, 0xe6,
  *                                  0x72, 0x67, 0x72, 0xf8, 0x64]);
  */
 const LATIN1 = const Latin1Codec();
 
 const int _LATIN1_MASK = 0xFF;
 
 /**
  * A [LatinCodec] encodes strings to ISO Latin-1 (aka ISO-8859-1) bytes
  * and decodes Latin-1 bytes to strings.
  */
-class Latin1Codec extends _Encoding {
+class Latin1Codec extends Encoding {
   final bool _allowInvalid;
   /**
    * Instantiates a new [Latin1Codec].
    *
    * If [allowInvalid] is true, the [decode] method and the converter
    * returned by [decoder] will default to allowing invalid values. Invalid
    * values are decoded into the Unicode Replacement character (U+FFFD).
    * Calls to the [decode] method can override this default.
    *
    * Encoders will not accept invalid (non Latin-1) characters.
    */
   const Latin1Codec({bool allowInvalid: false}) : _allowInvalid = allowInvalid;
 
+  String get name => "iso-8859-1";
+
   /**
    * Decodes the Latin-1 [bytes] (a list of unsigned 8-bit integers) to the
    * corresponding string.
    *
    * If [bytes] contains values that are not in the range 0 .. 255, the decoder
    * will eventually throw a [FormatException].
    *
    * If [allowInvalid] is not provided, it defaults to the value used to create
    * this [Latin1Codec].
    */
@@ skipping 98 matching lines @@
         }
       }
     }
     if (start < end) {
       _addSliceToSink(source, start, end, isLast);
     } else if (isLast) {
       close();
     }
   }
 }