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

runtime/vm/dart_api_impl.cc

 // 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.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 1566 matching lines @@
 
 
 static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
   void* new_ptr = realloc(reinterpret_cast<void*>(ptr), new_size);
   return reinterpret_cast<uint8_t*>(new_ptr);
 }
 
 
 DART_EXPORT bool Dart_Post(Dart_Port port_id, Dart_Handle handle) {
   DARTSCOPE(Thread::Current());
+  NoSafepointScope no_safepoint_scope;
   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);
+  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);
   intptr_t len = writer.BytesWritten();
   return PortMap::PostMessage(new Message(
       port_id, data, len, Message::kNormalPriority));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewSendPort(Dart_Port port_id) {
@@ skipping 4326 matching lines @@
                                    ApiReallocate);
   writer.WriteFullSnapshot();
   *vm_isolate_snapshot_size = writer.VmIsolateSnapshotSize();
   *isolate_snapshot_size = writer.IsolateSnapshotSize();
   *instructions_snapshot_size = writer.InstructionsSnapshotSize();
 
   return Api::Success();
 }
 
 }  // namespace dart