VM: [Kernel] Revert changes to the native ports that introduced peers.

runtime/bin/loader.cc

Index: runtime/bin/loader.cc
diff --git a/runtime/bin/loader.cc b/runtime/bin/loader.cc
index f92d13dfd88f519de169407c44f13157403dbd87..70ee44471d6628f2a7a1892515fe274d6a771c2b 100644
--- a/runtime/bin/loader.cc
+++ b/runtime/bin/loader.cc
@@ -34,8 +34,7 @@ Loader::Loader(IsolateData* isolate_data)
       payload_length_(0) {
   monitor_ = new Monitor();
   ASSERT(isolate_data_ != NULL);
-  port_ =
-      Dart_NewNativePort("Loader", Loader::NativeMessageHandler, false, this);
+  port_ = Dart_NewNativePort("Loader", Loader::NativeMessageHandler, false);
   isolate_data_->set_loader(this);
   AddLoader(port_, isolate_data_);
 }
@@ -818,10 +817,13 @@ Loader* Loader::LoaderFor(Dart_Port port) {
 
 
 void Loader::NativeMessageHandler(Dart_Port dest_port_id,
-                                  Dart_CObject* message,
-                                  void* peer) {
+                                  Dart_CObject* message) {
   MutexLocker ml(loader_infos_lock_);
-  static_cast<Loader*>(peer)->QueueMessage(message);
+  Loader* loader = LoaderForLocked(dest_port_id);
+  if (loader == NULL) {
+    return;
+  }
+  loader->QueueMessage(message);
 }
 
 }  // namespace bin