Fix inverted generic parameters.

lib/stream_channel.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 'package:async/async.dart';
 
 import 'src/stream_channel_transformer.dart';
 
@@ skipping 58 matching lines @@
   factory StreamChannel(Stream<T> stream, StreamSink<T> sink) =>
       new _StreamChannel<T>(stream, sink);
 
   /// Connects [this] to [other], so that any values emitted by either are sent
   /// directly to the other.
   void pipe(StreamChannel<T> other);
 
   /// Transforms [this] using [transformer].
   ///
   /// This is identical to calling `transformer.bind(channel)`.
-  StreamChannel transform(StreamChannelTransformer<dynamic, T> transformer);
+  StreamChannel transform(StreamChannelTransformer<T, dynamic> transformer);
 
   /// Transforms only the [stream] component of [this] using [transformer].
   StreamChannel<T> transformStream(StreamTransformer<T, T> transformer);
 
   /// Transforms only the [sink] component of [this] using [transformer].
   StreamChannel<T> transformSink(StreamSinkTransformer<T, T> transformer);
 
   /// Returns a copy of [this] with [stream] replaced by [change]'s return
   /// value.
   StreamChannel<T> changeStream(Stream<T> change(Stream<T> stream));
@@ skipping 16 matching lines @@
 }
 
 /// A mixin that implements the instance methods of [StreamChannel] in terms of
 /// [stream] and [sink].
 abstract class StreamChannelMixin<T> implements StreamChannel<T> {
   void pipe(StreamChannel<T> other) {
     stream.pipe(other.sink);
     other.stream.pipe(sink);
   }
 
-  StreamChannel transform(StreamChannelTransformer<dynamic, T> transformer) =>
+  StreamChannel transform(StreamChannelTransformer<T, dynamic> transformer) =>
       transformer.bind(this);
 
   StreamChannel<T> transformStream(StreamTransformer<T, T> transformer) =>
       changeStream(transformer.bind);
 
   StreamChannel<T> transformSink(StreamSinkTransformer<T, T> transformer) =>
       changeSink(transformer.bind);
 
   StreamChannel<T> changeStream(Stream<T> change(Stream<T> stream)) =>
       new StreamChannel(change(stream), sink);
 
   StreamChannel<T> changeSink(StreamSink<T> change(StreamSink<T> sink)) =>
       new StreamChannel(stream, change(sink));
 }