gui: Don't use newfangled ES6 features (fixes #5348)
gui: Don't use newfangled ES6 features (fixes #5348)

AudriusButkevicius/syncthing,wweich/syncthing,syncthing/syncthing,imsodin/syncthing,wweich/syncthing,uok/syncthing,syncthing/syncthing,syncthing/syncthing,wweich/syncthing,syncthing/syncthing,imsodin/syncthing,xduugu/syncthing,rumpelsepp/syncthing,rumpelsepp/syncthing,xduugu/syncthing,uok/syncthing,AudriusButkevicius/syncthing,imsodin/syncthing,syncthing/syncthing,uok/syncthing,AudriusButkevicius/syncthing,AudriusButkevicius/syncthing,imsodin/syncthing,imsodin/syncthing,rumpelsepp/syncthing,syncthing/syncthing,rumpelsepp/syncthing,xduugu/syncthing,xduugu/syncthing,uok/syncthing,wweich/syncthing