[FIX] prevent a crash in ie9 (invalid setTimeout) (bus)

The call to this.poll return undefined, and IE9 does not like undefined
values in a timeout.

addons/bus/static/src/js/bus.js

@@ -14,7 +14,7 @@
         },
         start_polling: function(){
             if(!this.activated){
-                setTimeout(this.poll(), 1);
+                this.poll();
                 this.stop = false;
             }
         },