[css3-exclusions] shape offsets should be relative to box-sizing property

Hi All,

Looking over the Exclusions and Shapes specification, I couldn't find a reference to what shape x and y offsets are relative to in a CSS property value like:
shape-inside: rectangle(10px, 10px, 80px, 80px);
I had originally assumed these offsets were relative to the content box [1], but as percentages are now resolved based on the box-sizing property [2], I think it would make sense to make a shape's x and y offsets relative to the same box.

As one additional question, are shape-outside and shape-inside positioned and sized based on the same box? I think this would make the most sense, but that would make shape-outside positioned based on the content box by default.

-Bear

[1] https://dl.dropbox.com/u/1558588/www-style/shape-offsets.png
[2] http://dev.w3.org/csswg/css3-exclusions/#basic-shapes-from-svg-syntax