[css3-grid-layout] grid-auto-flow values

Hi everyone,

currently grid-auto-flow accepts 3 values [1]:

none | rows | columns

For coherency with flexbox, it would nice to reuse values that match
the flex-direction [2]:

row | column

Apologies if this has already been discussed but I couldn't find any
discussion about renaming the values when the property was renamed to
grid-auto-flow [3].

Thanks,
Julien

[1] http://dev.w3.org/csswg/css3-grid-layout/#grid-auto-flow-property
[2] http://dev.w3.org/csswg/css3-flexbox/#flex-direction
[3] http://lists.w3.org/Archives/Public/www-style/2012Feb/0571.html