[HarfBuzz] order of glyphs presented to font features.

[Eric Muller]

It seems that when:

hb_buffer_set_script (fBuffer, HB_SCRIPT_ARABIC);
hb_buffer_set_direction (fBuffer, HB_DIRECTION_LTR);
hb_buffer_add_utf32 (fBuffer, "١٢");   // pseudo code, of 
course

then the glyphs are presented in the wrong order to the font features. 
You can see this with the font available at 
<http://fonts.qurancomplex.gov.sa/?page_id=42>. It's intended for the 
Quran (and only for the Quran; word doc at the same URL), and ligates 
sequences of digits for the end of ayah. The example above displays "end 
of ayah 21".

I am using a slightly old version of Harfbuzz, so may be this has been 
fixed?

Thanks,
Eric.