Use Uint8List for byte lists in dart:convert.

sdk/lib/convert/byte_conversion.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;
 
 /**
  * The [ByteConversionSink] provides an interface for converters to
  * efficiently transmit byte data.
  *
@@ skipping 60 matching lines @@
 /**
  * This class accumulates all chunks into one list of bytes
  * and invokes a callback when the sink is closed.
  *
  * This class can be used to terminate a chunked conversion.
  */
 class _ByteCallbackSink extends ByteConversionSinkBase {
   static const _INITIAL_BUFFER_SIZE = 1024;
 
   final _ChunkedConversionCallback<List<int>> _callback;
-  // TODO(11971, floitsch): use Uint8List instead of normal lists.
-  List<int> _buffer = new List<int>(_INITIAL_BUFFER_SIZE);
+  List<int> _buffer = new Uint8List(_INITIAL_BUFFER_SIZE);
   int _bufferIndex = 0;
 
   _ByteCallbackSink(void callback(List<int> accumulated))
       : this._callback = callback;
 
   void add(Iterable<int> chunk) {
     int freeCount = _buffer.length - _bufferIndex;
     if (chunk.length > freeCount) {
       // Grow the buffer.
       int oldLength = _buffer.length;
       int newLength = _roundToPowerOf2(chunk.length + oldLength) * 2;
-      // TODO(11971, floitsch): use Uint8List instead of normal lists.
-      List<int> grown = new List<int>(newLength);
+      List<int> grown = new Uint8List(newLength);
       grown.setRange(0, _buffer.length, _buffer);
       _buffer = grown;
     }
     _buffer.setRange(_bufferIndex, _bufferIndex + chunk.length, chunk);
     _bufferIndex += chunk.length;
   }
 
   static int _roundToPowerOf2(int v) {
     assert(v > 0);
     v--;
     v |= v >> 1;
     v |= v >> 2;
     v |= v >> 4;
     v |= v >> 8;
     v |= v >> 16;
     v++;
     return v;
   }
 
   void close() {
     _callback(_buffer.sublist(0, _bufferIndex));
   }
 }