bug#30800: 26.0.91; unknown crash on macos

[Eli Zaretskii]

> From: Aaron Jensen <aaronjensen@gmail.com>
> Date: Thu, 22 Mar 2018 18:49:33 -0700
> Cc: Alan Third <alan@idiocy.org>, 30800@debbugs.gnu.org
> 
> The patch appears to work. Not a single crash all day and no other ill
> effects afaict. The patch isn't a fix for a bug introduced in 26, but
> it does fix a bug that made more accessible by the frame changes in 26
> (and posframe). Would you consider it for emacs-26?

Yes, I'm okay with pushing this to emacs-26.

Thanks.