[css3-transitions] animation of color values should mention premultiplication

http://dev.w3.org/csswg/css3-transitions/#animation-of-property-types-
currently says:
  # color: interpolated via red, green, blue and alpha components
  # (treating each as a number, see below). 

This bullet point should probably mention that the red, green, and
blue values should NOT be premultiplied with the alpha.  (I think
that's the correct behavior, anyway.)

-David

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