bug#8429: 24.0.50; regression: `flush-lines' does not flush all it should

[Stefan Monnier]

> If I had to guess in ignorance I'd say that it has to do with Emacs 24
> highlighting only a screen at a time, instead of the whole buffer.
> For the part of the buffer that gets highlighted (so the escape chars
> are not apparent) there is no problem.

Sounds like the likely culprit.  And the fix is still the same: move the
grep-highlighting-processing from font-lock to the process filter.


        Stefan