Add Likely Subtags first step

[Doug Ewell]

Bérenger Enselme <berenger at enselme dot com> wrote:

> In http://www.unicode.org/reports/tr35/#Likely_Subtags the first step
> is described as canonicalization.
>
> The 3rd substep says to return a tag as is if it is in the <variable
> id="$grandfathered" type="choice"> from the supplemental data.
>
> As far as I can tell this never happens since such tags have already
> been replaced in the 2nd substep.
>
> Thinking about it more, I don't think any of the grandfathered tags
> would actually make it to the second substep since they wouldn't pass
> the first substep.

Not all grandfathered tags have a Preferred-Value. Canonicalization
leaves such tags unchanged. Examples include "cel-gaulish", "en-GB-oed",
and "i-mingo".

--
Doug Ewell | Thornton, CO, USA | http://ewellic.org