Remove references to non-existent messageExpired action

js/expiring_messages.js

@@ -39,12 +39,6 @@
           sentAt: message.get('sent_at'),
         });
 
-        Whisper.events.trigger(
-          'messageExpired',
-          message.id,
-          message.conversationId
-        );
-
         const conversation = message.getConversation();
         if (conversation) {
           conversation.trigger('expired', message);