Fix for issue 21398 (only send "literal like" objects across isolates spawned using spawnURI

runtime/bin/io_service_patch.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.
 
 patch class _IOService {
   // Lazy initialize service ports, 32 per isolate.
   static const int _SERVICE_PORT_COUNT = 32;
   static List<SendPort> _servicePort = new List(_SERVICE_PORT_COUNT);
   static RawReceivePort _receivePort;
   static SendPort _replyToPort;
   static Map<int, Completer> _messageMap = {};
   static int _id = 0;
 
   /* patch */ static Future dispatch(int request, List data) {
     int id;
     do {
       id = _getNextId();
     } while (_messageMap.containsKey(id));
     int index = id % _SERVICE_PORT_COUNT;
     _initialize(index);
     var completer = new Completer();
     _messageMap[id] = completer;
-    _servicePort[index].send([id, _replyToPort, request, data]);
+    try {
+      _servicePort[index].send([id, _replyToPort, request, data]);
+    } catch (error) {
+      _messageMap.remove(id).complete(error);
+      if (_messageMap.length == 0) {
+        _finalize();
+      }
+    }
     return completer.future;
   }
 
   static void _initialize(int index) {
     if (_servicePort[index] == null) {
       _servicePort[index] = _newServicePort();
     }
     if (_receivePort == null) {
       _receivePort = new RawReceivePort();
       _replyToPort = _receivePort.sendPort;
       _receivePort.handler = (data) {
         assert(data is List && data.length == 2);
         _messageMap.remove(data[0]).complete(data[1]);
         if (_messageMap.length == 0) {
-          _id = 0;
-          _receivePort.close();
-          _receivePort = null;
+          _finalize();
         }
       };
     }
   }
 
+  static void _finalize() {
+    _id = 0;
+    _receivePort.close();
+    _receivePort = null;
+  }
+
   static int _getNextId() {
     if (_id == 0x7FFFFFFF) _id = 0;
     return _id++;
   }
 
   static SendPort _newServicePort() native "IOService_NewServicePort";
 }