[HarfBuzz] Setting initial cluster value

[Simon Cozens]

On 26/06/2016 06:52, Kelvin Ma wrote:
> 
> ['t', 'h', 'i', 's', ' ', {FONT_POSITIVE: 'bold'}, 'i', 's', ' ', 'b',
> 'o', 'l', 'd', 'e', 'd', {FONT_NEGATIVE: 'bold'}, ' ', 't', 'e', 'x', 't']

You don't need to send your internal representation to Harfbuzz. If it's
a problem, you could always send something else instead.

In fact, you will need to, because bold characters usually have
different metrics to regular ones.