bug#57082: 29.0.50; emacs-news-view-mode breakage

[Juri Linkov]

>> Also don't understand why is this change:
>>
>>          (when outline-minor-mode-highlight
>> -          (if (and global-font-lock-mode (font-lock-specified-p major-mode))
>> -              (progn
>> -                (font-lock-add-keywords nil outline-font-lock-keywords t)
>> -                (font-lock-flush))
>> -            (outline-minor-mode-highlight-buffer)))
>> +          (when (and global-font-lock-mode (font-lock-specified-p 
>> major-mode))
>> +            (font-lock-add-keywords nil outline-font-lock-keywords t)
>> +            (font-lock-flush))
>> +          (outline-minor-mode-highlight-buffer))
>>
>> `outline-minor-mode-highlight-buffer' is intended only for buffers
>> that don't support font-lock highlighting.
>
> Yes, but with that change, arrows are displayed on first visiting the
> NEWS buffer; without it, they only appear when typing TAB on an outline
> heading.

This change broke fontification e.g. in diff buffers that now
add outline faces on diff hunks.  So we need another solution.
Maybe on first visiting the NEWS buffer better to call
refontification with font-lock-ensure?