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

tests/isolate/unresolved_ports_test.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.
 
 // spawns multiple isolates and sends unresolved ports between them.
 #library('unresolved_ports');
 #import('dart:isolate');
 #import('../../lib/unittest/unittest.dart');
 
 // This test does the following:
@@ skipping 33 matching lines @@
     SendPort tim = spawnFunction(timIsolate);
     SendPort beth = spawnFunction(bethIsolate);
 
     beth.send(
         // because tim is created asynchronously, here we are sending an
         // unresolved port:
         ['main says: Beth, find out if Tim is coming.', tim],
         port.toSendPort());
   });
 }