Bombe: Firefox optimisation
Bombe: Firefox optimisation

Switch a couple of for of loops in the critical path for classic fors.
This loses about 10% performance in Chrome, but it brings Firefox
performance in line with Chrome's, rather than 2.5 times slower.

gchq/CyberChef,artemisbot/CyberChef,gchq/CyberChef,artemisbot/CyberChef