Remove old isolate API and update all code in the repository to use

tests/isolate/v2_spawn_uri_child_isolate.dart

Index: tests/isolate/v2_spawn_uri_child_isolate.dart
diff --git a/tests/isolate/v2_spawn_uri_child_isolate.dart b/tests/isolate/v2_spawn_uri_child_isolate.dart
deleted file mode 100644
index 8b355308dd121d8e03616ab20fe05c88340c76ae..0000000000000000000000000000000000000000
--- a/tests/isolate/v2_spawn_uri_child_isolate.dart
+++ /dev/null
@@ -1,11 +0,0 @@
-// 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() {
-  port.receive((msg, reply) => reply.send('re: $msg'));
-}