[css3-writing-modes] computed value of text-combine-horizontal digits values

While working on implementing support for 'text-combine-horizontal', I
noticed what seems to be a small problem with the definition of
computed value for 'text-combine-horizontal'.

The 'digits' value of 'text-combine-horizontal' is defined to take an
optional <integer> value.  If this is omitted, the value defaults to 2.

http://dev.w3.org/csswg/css-writing-modes/#text-combine-horizontal

The computed value is given as "specified value" so I think that
implies that 'digits' and 'digits 2' need to be distinguished.  Since
internally there's no reason to make this distinction, I think it
would be better to define the computed in such a way that the computed
values of the property definitions below are equivalent:

  text-combine-horizontal: digits;    /* computed value: 'digits' */
  text-combine-horizontal: digits 2;  /* computed value: 'digits'? */

Not sure what the right wording is for this, I'll defer to those with 
better OM chops.

Cheers,

John Daggett