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

runtime/vm/native_api_impl.cc

Index: runtime/vm/native_api_impl.cc
diff --git a/runtime/vm/native_api_impl.cc b/runtime/vm/native_api_impl.cc
index c707c9e9cf776f4b752becc58dedc150cdd3a504..2345b465323c2abbd3404b2018c200992d2f6833 100644
--- a/runtime/vm/native_api_impl.cc
+++ b/runtime/vm/native_api_impl.cc
@@ -56,6 +56,17 @@ DART_EXPORT bool Dart_PostCObject(Dart_Port port_id, Dart_CObject* message) {
 }
 
 
+DART_EXPORT bool Dart_PostInteger(Dart_Port port_id, intptr_t message) {
+  if (!Smi::IsValid(message)) {
+    return false;
+  }
+  Message* msg = new Message(port_id, message, Message::kNormalPriority);
+
+  // Post the message at the given port.
+  return PortMap::PostMessage(msg);
+}
+
+
 DART_EXPORT Dart_Port Dart_NewNativePort(const char* name,
                                          Dart_NativeMessageHandler handler,
                                          bool handle_concurrently) {