bug#33729: 27.0.50; Partial glyphs not rendered for Gujarati with Harfbuzz enabled (renders fine using m17n)

[Eli Zaretskii]

> Date: Sat, 22 Dec 2018 17:49:45 +0200
> From: Khaled Hosny <dr.khaled.hosny@gmail.com>
> Cc: rgm@gnu.org, far.nasiri.m@gmail.com, behdad@behdad.org,
>       33729@debbugs.gnu.org, kaushal.modi@gmail.com
> 
> Yes, the standard Unicode composition and decomposition. HarfBuzz uses
> these during shaping (it prefers composed form for a given sequence if
> supported by the font, and falls back to decomposed form otherwise).

Btw, how is this problem solved in the other projects that use
Harfuzz?  Does every project need to provide this functionality, or
does Harfuzz have it built-in, like with the script tags?  If there's
built-in support for this, perhaps Emacs could just use that?