Adds a special case for sending an int over a port with the native API.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index f607b189a0cd005500ddd7ce5959c4976a70e346..868a920c9f11428d8546d210d706530dccf6060e 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -1587,7 +1587,15 @@ DART_EXPORT bool Dart_Post(Dart_Port port_id, Dart_Handle handle) {
   if (port_id == ILLEGAL_PORT) {
     return false;
   }
-  const Object& object = Object::Handle(Z, Api::UnwrapHandle(handle));
+
+  // Smis and null can be sent without serialization.
+  RawObject* raw_obj = Api::UnwrapHandle(handle);

[Ivan Posva, 2015/12/11 21:02:38]

Please make sure that this code is wrapped in a NoSafepointScope as you have a
naked RawObject sitting around here.

[zra, 2015/12/11 22:01:30]

Done.

+  if (ApiObjectConverter::CanConvert(raw_obj)) {
+    return PortMap::PostMessage(new Message(
+        port_id, raw_obj, Message::kNormalPriority));
+  }
+
+  const Object& object = Object::Handle(Z, raw_obj);
   uint8_t* data = NULL;
   MessageWriter writer(&data, &allocator, false);
   writer.WriteMessage(object);