Re: master 7362554: Widen around c-font-lock-fontify-region. This fixes bug #38049.

[Dmitry Gutov]

On 14.11.2019 21:19, Eli Zaretskii wrote:
> So we are going to do such changes in every application that calls
> vertical-motion, directly or indirectly?  And what about
> posn-at-point, or pos-visible-in-window-p, or any other API that uses
> the display code internally? are we going to fix their callers as
> well?  That really makes no sense, so I very much hope I somehow
> grossly misunderstand what you are suggesting as a fix.

Your objections are on point, of course.

It's not a comprehensive fix, but it should be an improvement anyway (at 
least for performance).

> So you are saying that we should enlarge jit-lock-chunk-size to
> most-positive-fixnum?  I don't think so.

No, it's more about the number of calls to font-lock functions. I.e. 
fontifying line-by-line vs. doing it in a larger block. The size of that 
block is not so important, as long as it's much bigger than a line.