Fix all strong-mode errors and warnings.

lib/html.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:typed_data';
 
 import 'package:async/async.dart';
 import 'package:stream_channel/stream_channel.dart';
@@ skipping 97 matching lines @@
         onDone: () => _webSocket.close(_localCloseCode, _localCloseReason));
   }
 }
 
 /// A [WebSocketSink] that tracks the close code and reason passed to [close].
 class _HtmlWebSocketSink extends DelegatingStreamSink implements WebSocketSink {
   /// The channel to which this sink belongs.
   final HtmlWebSocketChannel _channel;
 
   _HtmlWebSocketSink(HtmlWebSocketChannel channel)
-      : super(channel._controller.foreign.sink),
-        _channel = channel;
+      : _channel = channel,
+        super(channel._controller.foreign.sink);
 
   Future close([int closeCode, String closeReason]) {
     _channel._localCloseCode = closeCode;
     _channel._localCloseReason = closeReason;
     return super.close();
   }
 }
 
 /// An enum for choosing what type [HtmlWebSocketChannel] emits for binary
 /// messages.
 class BinaryType {
   /// Tells the channel to emit binary messages as [Blob]s.
   static const blob = const BinaryType._("blob", "blob");
 
   /// Tells the channel to emit binary messages as [Uint8List]s.
   static const list = const BinaryType._("list", "arraybuffer");
 
   /// The name of the binary type, which matches its variable name.
   final String name;
 
   /// The value as understood by the underlying [WebSocket] API.
   final String value;
 
   const BinaryType._(this.name, this.value);
 
   String toString() => name;
 }