use async and enable compression in example

R=nweiz@google.com

Review URL: https://codereview.chromium.org//1660513002 .
diff --git a/example/example_server.dart b/example/example_server.dart
index 5abc65e..195e48e 100644
--- a/example/example_server.dart
+++ b/example/example_server.dart
@@ -5,14 +5,17 @@
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:shelf/shelf_io.dart' as io;
 
-void main() {
+main() async {
   var handler = const shelf.Pipeline()
       .addMiddleware(shelf.logRequests())
       .addHandler(_echoRequest);
 
-  io.serve(handler, 'localhost', 8080).then((server) {
-    print('Serving at http://${server.address.host}:${server.port}');
-  });
+  var server = await io.serve(handler, 'localhost', 8080);
+
+  // Enable content compression
+  server.autoCompress = true;
+
+  print('Serving at http://${server.address.host}:${server.port}');
 }
 
 shelf.Response _echoRequest(shelf.Request request) {
diff --git a/pubspec.yaml b/pubspec.yaml
index 0c33a02..6ab9930 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: shelf
-version: 0.6.5
+version: 0.6.6-dev
 author: Dart Team <misc@dartlang.org>
 description: Web Server Middleware for Dart
 homepage: https://github.com/dart-lang/shelf
diff --git a/test/message_test.dart b/test/message_test.dart
index 7caad9a..51596cb 100644
--- a/test/message_test.dart
+++ b/test/message_test.dart
@@ -6,7 +6,6 @@
 import 'dart:convert';
 
 import 'package:shelf/src/message.dart';
-import 'package:shelf/src/response.dart';
 import 'package:test/test.dart';
 
 import 'test_util.dart';