Delete NativeMessageHandler once a native port closes.

runtime/vm/native_message_handler.cc

 // Copyright (c) 2012, 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 "vm/native_message_handler.h"
 
 #include "vm/dart_api_message.h"
 #include "vm/isolate.h"
 #include "vm/message.h"
 #include "vm/snapshot.h"
 
 namespace dart {
 
 NativeMessageHandler::NativeMessageHandler(const char* name,
                                            Dart_NativeMessageHandler func)
     : name_(strdup(name)),
       func_(func) {
-  // A NativeMessageHandler always has one live port.
-  increment_live_ports();
 }
 
 
 NativeMessageHandler::~NativeMessageHandler() {
   free(name_);
 }
 
 
 #if defined(DEBUG)
 void NativeMessageHandler::CheckAccess() {
@@ skipping 14 matching lines @@
   ApiNativeScope scope;
   Dart_CObject* object;
   ApiMessageReader reader(message);
   object = reader.ReadMessage();
   (*func())(message->dest_port(), object);
   delete message;
   return kOK;
 }
 
 }  // namespace dart