Create message port between parent and child thread

create_message_port.cc

void Worker::CreateEnvMessagePort(Environment* env) {
  HandleScope handle_scope(isolate_);
  Mutex::ScopedLock lock(mutex_);
  // Set up the message channel for receiving messages in the child.
  child_port_ = MessagePort::New(env,
                                 env->context(),
                                 std::move(child_port_data_));
  // MessagePort::New() may return nullptr if execution is terminated
  // within it.
  if (child_port_ != nullptr)
    env->set_message_port(child_port_->object(isolate_));
}