Update to Firefox 55.0.X

[robbiemacg]

For now, I think I've verified experimentally that that new release is trying to do something to sanitize data/files that my previous release was not. Those files which were failing to display all began with a wildcard import statement (something like, import java.util.*. Adding a comment at the beginning of the file results in a change in browser behaviour, and files are displayed as text once again... So, the plot thickens.