First experimental steps towards a better story for JS interop.

lib/isolate/frog/messages.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.
 
 // Defines message visitors, serialization, and deserialization.
 
 /** Serialize [message] (or simulate serialization). */
 _serializeMessage(message) {
   if (_globalState.needSerialization) {
     return new _JsSerializer().traverse(message);
@@ skipping 13 matching lines @@
 }
 
 class _JsSerializer extends _Serializer {
 
   _JsSerializer() : super() { _visited = new _JsVisitedMap(); }
 
   visitSendPort(SendPort x) {
     if (x is _NativeJsSendPort) return visitNativeJsSendPort(x);
     if (x is _WorkerSendPort) return visitWorkerSendPort(x);
     if (x is _BufferingSendPort) return visitBufferingSendPort(x);
-    throw "Illegal underlying port $p";
+    throw "Illegal underlying port $x";
   }
 
   visitNativeJsSendPort(_NativeJsSendPort port) {
     return ['sendport', _globalState.currentManagerId,
         port._isolateId, port._receivePort._id];
   }
 
   visitWorkerSendPort(_WorkerSendPort port) {
     return ['sendport', port._workerId, port._isolateId, port._receivePortId];
   }
@@ skipping 110 matching lines @@
     return new _JsCopier().traverse(x);
   }
 
   // only visible for testing purposes
   static serialize(x) {
     _Serializer serializer = new _JsSerializer();
     _Deserializer deserializer = new _JsDeserializer();
     return deserializer.deserialize(serializer.traverse(x));
   }
 }