The Tor Browser / file revision

 <!-- This SVG file uses itself as an image.  Currently, we don't paint

      recursively-referenced images beyond the first level.  When this testcase

      is viewed directly, it gets treated as a document (not an image), so its

      <image> element is painted.  However, the <image>'s own *internal* <image>

      element does *not* get painted.  So we end up painting two blue circles:

      one for the <circle> and one for the <image>'s <circle> (and no more). -->

 <svg xmlns="http://www.w3.org/2000/svg"

      xmlns:xlink="http://www.w3.org/1999/xlink"

      width="100" height="100">

   <circle cx="10" cy="10" r="10" fill="blue"/>

   <image x="20" y="20" width="100" height="100"

          xlink:href="#foo"/>

   <!-- When used as a URL, #foo evaluates to ${my_url}#foo, which (when treated

        as an image URL) just turns into ${my_url}. -->

 </svg>