Remove the reply port form the native isolate handler

runtime/include/dart_native_api.h

Index: runtime/include/dart_native_api.h
diff --git a/runtime/include/dart_native_api.h b/runtime/include/dart_native_api.h
index cdfc5df777a3823bf4e89a19fa21f7eb2178386a..ffadba8656927609ebe1fa890f9d25309663a9d4 100644
--- a/runtime/include/dart_native_api.h
+++ b/runtime/include/dart_native_api.h
@@ -39,6 +39,7 @@ typedef enum {
   Dart_CObject_kArray,
   Dart_CObject_kTypedData,
   Dart_CObject_kExternalTypedData,
+  Dart_CObject_kSendPort,
   Dart_CObject_kUnsupported,
   Dart_CObject_kNumberOfTypes
 } Dart_CObject_Type;
@@ -52,6 +53,7 @@ typedef struct _Dart_CObject {
     double as_double;
     char* as_string;
     char* as_bigint;
+    Dart_Port as_send_port;
     struct {
       intptr_t length;
       struct _Dart_CObject** values;
@@ -101,8 +103,7 @@ DART_EXPORT bool Dart_PostCObject(Dart_Port port_id, Dart_CObject* message);
  */
 
 typedef void (*Dart_NativeMessageHandler)(Dart_Port dest_port_id,
-Dart_Port reply_port_id,
-Dart_CObject* message);
+                                          Dart_CObject* message);
 
 /**
  * Creates a new native port.  When messages are received on this