[HarfBuzz] Matra after Matra is not allowed in Brahmi Based Script (bug in harfbuzz)

[Pravin Satpute]

Hi,

    Just today saw one bug in harfbuzz, type ??? (0915, 09ef, 09ef) in
kwrite.

    Actually first syllable is valid (0915 093f) and second is invalid
(09ef), but kwrite recognize it as complete syllable that is wrong.

    Matra [093e to 094c] after matra [093e to 094c],  forms second matra
as a invalid syllable, same way it apply to other brahmi based script as
well, just there are some exception, even that should not allowed since,
Unicode specifically given complete matra for that purpose only.

    Dunno how people started using matra's in its split form, i guess
this is started from 8bit solutions where reordering was not possible,
but even if people are using some exceptional condition it should be
handled differently as handled for bengali and tamil.

    attached patch to fix this


Thanks,
Pravin S


 *Description*  	
   ??? (0915, 09ef, 09ef) type this in kwrite actually first syllable is
(0915 093f) and second is invalid (09ef), but kwrite recognize it as
complete syllable that is wrong so matra [093e to 094c] after matra
[093e to 094c] forms a second matra as a invalid syllable same way it
apply to other brahmi based script, just there are some exception, even
that should not allowed since, Unicode specifically given complete matra
for that purpose only. but due to some bugs/ or problem people started
using it. but even in that case only some cases should be handled as
exception
	Show » <http://bugreports.qt.nokia.com/browse/QTBUG-13545>


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