bug#21165: 25.0.50; line-spacing missing on empty lines

[Eli Zaretskii]

> From: Ingo Lohmar <i.lohmar@gmail.com>
> Date: Fri, 31 Jul 2015 15:16:36 +0200
> 
> 
> 1. On a graphical display, (setq-default line-spacing 2).
> 2. In *scratch*, type a few lines, with one line empty in between:
> This
> is
> 
> a
> simple test.
> 3. Go to the empty line and insert a single character.  The text below
>    is pushed down by `line-spacing' pixels.

Thanks, I fixed this in commit e91d2b3.