Honestly I've just set up a user CSS sheet that forces left justify. It makes the internet more comfortable, and has practically no downsides / bad interactions, unlike many such overrides.
This led to the CSS `text-wrap` property, and `text-wrap: pretty`[2], but pretty is not supported in FF yet, and the value `pretty` doesn't mandate Knuth's algorithm.
[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=630181
[2]: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/P...