Remove static clues from spawn_uri_child_isolate.dart

tests/isolate/spawn_uri_child_isolate.dart

 // Copyright (c) 2012, 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.
 
 // Child isolate code to be spawned from a URI to this file.
 library SpawnUriChildIsolate;
-import 'dart:isolate';
 
-void main(List<String> args, SendPort replyTo) {
+void main(List<String> args, replyTo) {
   var data = args[0];
   replyTo.send('re: $data');
 }