Update message-bus.js
Update message-bus.js

added async: true as an explicit option instead of the default value as Firefox seems to intermittently hang up the UI during a long poll without a default
SamSaffron/message_bus,MadBomber/message_bus,cannikin/message_bus,MadBomber/message_bus,cannikin/message_bus,cannikin/message_bus,SamSaffron/message_bus,MadBomber/message_bus