Fix enter to send chat

app/code/Magento/Messaging/view/frontend/templates/room.phtml

@@ -69,6 +69,8 @@
     }
     function send2(e) {
         if (e.keyCode == 13) {
+            var sender = document.getElementById("sender").value;
+            var receiver = document.getElementById("receiver").value;
             var message = document.getElementById("message").value;
             if (message != "") {
                 myFirebase.push({