[HarfBuzz] Hebrew composition to presentation forms

[Khaled Hosny]

Hi,

Someone reported an issue with the hireq placement under the yodh with
Ezra SIL font[1]. When I checked this, it seemed to be because HarfBuzz
is composing U+05D9 + U+05B4 to U+FB1D and the font has a glyph for
U+FB1D that has a not so good placement for hireq.

I thought this composition is result of Unicode normalisation, so
HarfBuzz is doing the right thing, but the comment in
hb-ot-shape-complex-hebrew.cc:75 indicates otherwise. I’m no very sure,
but I feel this kind of composition should fits more into fallback
shaping like done with Arabic and not something to be done
unconditionally, WDYT?

Regards,
Khaled

1. http://tex.stackexchange.com/q/156775/729