[css3-background] number of layers should consider background-origin and background-clip

http://dev.w3.org/csswg/css3-background/#layering says that the
number of background layers considers the background-image,
backgroundrepeat, background-size, and background-position
properties, but not the background-clip and background-origin
properties.

I think the number of layers should consider either (a) all six
properties or (b) only background-image.

Furthermore, the statement about interpreting each of the properties
as though it has a certain number of values should refer to all six
properties.

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/