[widgets] Step 5 - allowing private use lang tags

In Step 5 [1], the spec reads:

"If this range begins with the subtag "i", "x", or the range is marked
as "deprecated" in the IANA Language Subtag Registry, skip all the
steps in this algorithm below, and move onto the next range."

I believe that, at least, we should allow "x" (as in "x-secret-lang").
The user agent is going to ignore sub-tags it does not know anyway.

Proposed change:

[[
"If this range begins with the subtag "i" or the range is marked as
"deprecated" in the IANA Language Subtag Registry, skip all the steps
in this algorithm below, and move onto the next range."
]]


[1] http://dev.w3.org/2006/waf/widgets/Overview_TSE.html#step-5--derive-the-user-agents-locale

-- 
Marcos Caceres
http://datadriven.com.au