Firefox's support for word-break: break-all is a bit broken itself. It

seems to have some long-standing known failures (as reported in Bugzilla

and demonstrated in regression test suites), and the one that was

brought to our attention is that it does the wrong thing when working

with pre-formatted text with tabstops.
What ends up happening is that lines with tabs end up failing to

overflow soon enough, pushing the rest of the content off the screen. We

see this in diffs where the first column with tabs ends up taking the

majority of the width of the page.
In all other browsers, this behaves as expected, and in fact if we

change this to word-break: break-word instead of break-all, we get

the right behavior.
We still want break-all more generally, so we now include a rule

specifically for tabs to use break-word instead. This ensures proper

breaks and wrapping on Firefox and on all other major browsers.

Verified with some code provided by a customer. Without this fix,

lines fail to break when they should, causing layout problems, when

viewed in Firefox (across a wide range of versions). With the fix,

diffs look as they should.