Remove check for `@` and for `allow_non_roster_messaging`

The second especially doesn't make sense and I'm currently not aware of
a case headline stanzas with a JIDs containing `@` and with a body
exist.

dist/converse.js

@@ -66434,13 +66434,8 @@ var __WEBPACK_AMD_DEFINE_FACTORY__, __WEBPACK_AMD_DEFINE_ARRAY__, __WEBPACK_AMD_
         const from_jid = message.getAttribute('from');
 
         if (utils.isHeadlineMessage(_converse, message)) {
-          if (_.includes(from_jid, '@') && !_converse.allow_non_roster_messaging) {
-            return;
-          }
-
           if (_.isNull(message.querySelector('body'))) {
-            // Avoid creating a chat box if we have nothing to show
-            // inside it.
+            // Avoid creating a chat box if we have nothing to show inside it.
             return;
           }
 
@@ -66458,12 +66453,13 @@ var __WEBPACK_AMD_DEFINE_FACTORY__, __WEBPACK_AMD_DEFINE_ARRAY__, __WEBPACK_AMD_
             'stanza': message
           });
         }
-
-        return true;
       }
 
       function registerHeadlineHandler() {
-        _converse.connection.addHandler(onHeadlineMessage, null, 'message');
+        _converse.connection.addHandler(message => {
+          onHeadlineMessage(message);
+          return true;
+        }, null, 'message');
       }
 
       _converse.on('connected', registerHeadlineHandler);

src/converse-headline.js

@@ -114,12 +114,8 @@
                 /* Handler method for all incoming messages of type "headline". */
                 const from_jid = message.getAttribute('from');
                 if (utils.isHeadlineMessage(_converse, message)) {
-                    if (_.includes(from_jid, '@') && !_converse.allow_non_roster_messaging) {
-                        return;
-                    }
                     if (_.isNull(message.querySelector('body'))) {
-                        // Avoid creating a chat box if we have nothing to show
-                        // inside it.
+                        // Avoid creating a chat box if we have nothing to show inside it.
                         return;
                     }
                     const chatbox = _converse.chatboxes.create({
@@ -131,11 +127,13 @@
                     chatbox.createMessage(message, message);
                     _converse.emit('message', {'chatbox': chatbox, 'stanza': message});
                 }
-                return true;
             }
 
             function registerHeadlineHandler () {
-                _converse.connection.addHandler(onHeadlineMessage, null, 'message');
+                _converse.connection.addHandler(message => {
+                    onHeadlineMessage(message);
+                    return true;
+                }, null, 'message');
             }
             _converse.on('connected', registerHeadlineHandler);
             _converse.on('reconnected', registerHeadlineHandler);