Bring in the latest version of the SDK's WebSocket impl.

lib/src/copy/bytes_builder.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.
 
 // This is a copy of "dart:io"'s BytesBuilder implementation, from
 // sdk/lib/io/bytes_builder.dart. It's copied here to make it available to
 // non-"dart:io" applications (issue 18348).
 //
 // Because it's copied directly, there are no modifications from the original.
 //
 // This is up-to-date as of sdk revision
-// 86227840d75d974feb238f8b3c59c038b99c05cf.
+// e41fb4cafd6052157dbc1490d437045240f4773f.
+
 import 'dart:math';
 import 'dart:typed_data';
 
 /**
  * Builds a list of bytes, allowing bytes and lists of bytes to be added at the
  * end.
  *
  * Used to efficiently collect bytes and lists of bytes.
  */
 abstract class BytesBuilder {
@@ skipping 92 matching lines @@
     if (bytes is Uint8List) {
       _buffer.setRange(_length, required, bytes);
     } else {
       for (int i = 0; i < bytesLength; i++) {
         _buffer[_length + i] = bytes[i];
       }
     }
     _length = required;
   }
 
-  void addByte(int byte) => add([byte]);
+  void addByte(int byte) { add([byte]); }
 
   List<int> takeBytes() {
     if (_buffer == null) return new Uint8List(0);
     var buffer = new Uint8List.view(_buffer.buffer, 0, _length);
     clear();
     return buffer;
   }
 
   List<int> toBytes() {
     if (_buffer == null) return new Uint8List(0);
@@ skipping 19 matching lines @@
     x |= x >> 4;
     x |= x >> 8;
     x |= x >> 16;
     return x + 1;
   }
 }
 
 
 class _BytesBuilder implements BytesBuilder {
   int _length = 0;
-  final List _chunks = [];
+  final _chunks = <List<int>>[];
 
   void add(List<int> bytes) {
     if (bytes is! Uint8List) {
       bytes = new Uint8List.fromList(bytes);
     }
     _chunks.add(bytes);
     _length += bytes.length;
   }
 
-  void addByte(int byte) => add([byte]);
+  void addByte(int byte) { add([byte]); }
 
   List<int> takeBytes() {
     if (_chunks.length == 0) return new Uint8List(0);
     if (_chunks.length == 1) {
       var buffer = _chunks.single;
       clear();
       return buffer;
     }
     var buffer = new Uint8List(_length);
     int offset = 0;
@@ skipping 20 matching lines @@
 
   bool get isEmpty => _length == 0;
 
   bool get isNotEmpty => _length != 0;
 
   void clear() {
     _length = 0;
     _chunks.clear();
   }
 }