Update ZLib/GZip in dart:io to be a Codec/Converter from dart:convert.

sdk/lib/io/http_impl.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.io;
 
 class _HttpIncoming extends Stream<List<int>> {
   final int _transferLength;
   final Completer _dataCompleter = new Completer();
   Stream<List<int>> _stream;
@@ skipping 225 matching lines @@
           return request.close();
         });
   }
 
   StreamSubscription<List<int>> listen(void onData(List<int> event),
                                        {void onError(error),
                                         void onDone(),
                                         bool cancelOnError}) {
     var stream = _incoming;
     if (headers.value(HttpHeaders.CONTENT_ENCODING) == "gzip") {
-      stream = stream.transform(new ZLibInflater());
+      stream = stream.transform(GZIP.decoder);
     }
     return stream.listen(onData,
                          onError: onError,
                          onDone: onDone,
                          cancelOnError: cancelOnError);
   }
 
   Future<Socket> detachSocket() {
     _httpClient._connectionClosed(_httpRequest._httpClientConnection);
     return _httpRequest._httpClientConnection.detachSocket();
@@ skipping 252 matching lines @@
     return _writeHeaders()
         .then((_) {
           int contentLength = headers.contentLength;
           if (_ignoreBody) {
             stream.drain().catchError((_) {});
             return _headersSink.close();
           }
           stream = stream.transform(new _BufferTransformer());
           if (headers.chunkedTransferEncoding) {
             if (_asGZip) {
-              stream = stream.transform(new ZLibDeflater(gzip: true, level: 6));
+              stream = stream.transform(GZIP.encoder);
             }
             stream = stream.transform(new _ChunkedTransformer());
           } else if (contentLength >= 0) {
             stream = stream.transform(
                 new _ContentLengthValidator(contentLength, _uri));
           }
           return _headersSink.addStream(stream);
         });
   }
 
@@ skipping 1936 matching lines @@
   final Uri location;
 }
 
 String _getHttpVersion() {
   var version = Platform.version;
   // Only include major and minor version numbers.
   int index = version.indexOf('.', version.indexOf('.') + 1);
   version = version.substring(0, index);
   return 'Dart/$version (dart:io)';
 }