[CSSOM] suggestion for Computed Styles

I suggest adding a way of getting, for a given element or pseudo-elt
on a given element, a CSSStyleDeclaration of computed values that differ
from the initial value. That would be ***extremely*** useful for

   1. wysiwyg copy/paste between editable documents
   2. transformation of stylesheets into inline styles so XSL-FO
      can process and print easily HTML
   3. optimization of sylesheets

</Daniel>