Modernize the package's style.

test/stream_zip_test.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.
 
 import "dart:async";
-import "package:async/stream_zip.dart";
+
+import "package:async/async.dart";
 import "package:test/test.dart";
 
 /// Create an error with the same values as [base], except that it throwsA
 /// when seeing the value [errorValue].
 Stream streamError(Stream base, int errorValue, error) {
   return base.map((x) => (x == errorValue) ? throw error : x);
 }
 
 /// Make a [Stream] from an [Iterable] by adding events to a stream controller
 /// at periodic intervals.
@@ skipping 209 matching lines @@
       } else if (ctr == 2) {
         sub.pause();
         new Future.delayed(const Duration(milliseconds: 25)).then((_) {
           sub.resume();
         });
       }
       ctr++;
     }, count: 4));
   });
 }