Remove ID map in pad chat to save network and CPU usage

www/common/outer/messenger.js

@@ -537,6 +537,15 @@ define([
             if (peer === hk) { return; }
             if (channel.readOnly) { return; }
 
+            // XXX review
+            // Sending myData is used to build a "mapId" object which links
+            // netflux IDs to a curvePublic/uid. We use this map in friend chat
+            // to detect is the other user is online and we also use it in team chat
+            // to show if other team members are online (in the roster section).
+            // It is not needed in the pad chat for now and only causes useless
+            // network usage.
+            if (channel.isPadChat) { return; }
+
             // Join event will be sent once we are able to ID this peer
             var myData = createData(proxy);
             delete myData.channel;