bug#20628: 25.0.50; Incorrect line height for some fonts

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Cc: clement.pitclaudel@live.com,  20628@debbugs.gnu.org
> Date: Mon, 01 Jun 2015 12:54:28 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I couldn't actually reproduce such crashes on my system, but I made a
> > few changes that hopefully will prevent them.  Could you please see if
> > the latest branch tip still crashes under some circumstances?
> 
> Thanks, the crash no longer occurs with your latest change.

Great!

I will wait a few more days, in the hope that more people could check
out the branch and provide feedback, and will merge it then, barring
any new problems.

(Could someone please test this on NS?)

Thank you and Clement for your help in testing these non-trivial
changes.