Modernize the package's style.

lib/src/result/capture_transformer.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 '../result.dart';
+import 'capture_sink.dart';
+
+/// Use [Result.captureTransformer] instead.
+@Deprecated("Will be removed in async 2.0.0.")
+class CaptureStreamTransformer<T> implements StreamTransformer<T, Result<T>> {
+  const CaptureStreamTransformer();
+
+  Stream<Result<T>> bind(Stream<T> source) {
+    return new Stream<Result<T>>.eventTransformed(source, _createSink);
+  }
+
+  static EventSink _createSink(EventSink<Result> sink) {
+    return new CaptureSink(sink);
+  }
+}