[css-counter-styles] speak-as: auto and the override system

http://dev.w3.org/csswg/css-counter-styles/#counter-style-speak-as
says, when describing the 'auto' value:
  # If the system is override, this value has the same effect as the
  # overridden style’s speak-as.

This has an unusual interaction with the definition of the override
system, which says in
http://dev.w3.org/csswg/css-counter-styles/#valuedef-override that:
  # If a counter style uses the override system, any unspecified
  # descriptors must be taken from the overridden counter style
  # specified, rather than taking their initial values. 

It means that when the override system is used, speak-as: auto is
equivalent to having an omitted speak-as, and is *not* equivalent to
the overridden system having speak-as: auto.  Both of these seem
wrong to me.

Instead, I would propose that the 'auto' value say:
  # If the system is override, this value has the same effect that
  # 'auto' would have for the overridden counter style.
which seems more consistent with how the override system otherwise
works.

I think this proposal also slightly simplifies the loop detection
needed for speak-as (since it means that an explicit 'auto' value
can't loop into a further chain of 'speak-as' links).

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)