[cssom][css-grid] maintaining "resolved value"

As per http://lists.w3.org/Archives/Public/www-style/2013Sep/0468.html , it
was decided that "gCS returns used values for grid-template-rows/columns".

While I respect this decision for reasons of practicality, it creates
another special snowflake case for the definition of "resolved value", and
is in danger of setting a precedent for how window.getComputedStyle()
should work.

As per my understanding, the only reason gCS ever returned a used value was
due to the change in definition of "computed value" between CSS2 and
CSS2.1, with a preference for it returning computed value except in those
cases in which legacy code already had been expecting it to return a used
value.

My concern is that this opens the door for more caveats down the road, and
the reasoning behind the decision, at least according to the minutes,
sounded rather halfhearted:

  fantasai: Back to getComputedStyle.
>   fantasai: For compat with MS's impl, we're having gCS return the used
>             value rather than the computed value of these properties.
>   fantasai: We didn't see a clear path to make this consistent, and gCS
>             is already inconsistent anyway, so whatever.
>   fantasai: Any concerns?
>   dbaron: I'm in favor of having them all be computed values, but I guess
>           I'm okay.
>   fantasai: We felt the same way.
>   Rossen: Tooling was a big thing for us.
>   RESOLVED: gCS returns used values for grid-template-rows/columns.


Some more clarity from Rossen around how having a used value helped with
tooling would perhaps help me understand the decision better.

I'm not asking for any action, per se, but I'm just raising a general
concern for the size of the already long caveat list for "resolved value":
http://dev.w3.org/csswg/cssom/#resolved-values

-- 
Mike Sherov
Chief Technologist
SNAP Interactive, Inc. | Ticker: STVI
http://snap-interactive.com | http://ayi.com