Filling multi-line comments in `css-mode' is broken. Consider for
instance the following comment:

  /*
   * Multi-line comment here.
   * This comment spans
   * multiple
   * lines.
   * Better fill it!
   */

Filling it with a `fill-column' of 70, I'd expect the following
result:

  /*
   * Multi-line comment here.  This comment spans multiple lines.
   * Better fill it!
   */

But as of now, what we get is this:

  /* * Multi-line comment here.  * This comment spans * multiple *
  lines.  * Better fill it!  */

 From this comment in `css-fill-paragraph', it sounds like it is
supposed to work, or has been working some time before:

  ;; Filling inside a comment whose comment-end marker is not \n.
  ;; This code is meant to be generic, so that it works not only for
  ;; css-mode but for all modes.

Could someone fill me in?

Alternatively, we could let `css-mode' borrow comment filling code
from `cc-mode', like `js-mode' and `js2-mode' do. Please let me know
if that would be an acceptable fix.

-- Simen