[css3-writing-modes] fit-content equation is backwards from the CSS2.1 spec

I'm trying to implement the writing mode width and height keywords in
webkit and I realized the equation is backwards in the spec from the one it
references.

http://dev.w3.org/csswg/css3-writing-modes/#intrinsic-sizing

max(min-content, min(max-content, fill-available))

http://www.w3.org/TR/CSS21/visudet.html#float-width

min(max(preferred minimum width, available width), preferred width)

which seems to be equivalent with the new keywords to:

min(max-content, max(min-content, fill-available))

Which is indeed what the code in Webkit currently does for the keyword
"intrinsic" (old name for fit-content) and for floats.

- Elliott