The Tor Browser / file revision

 <!--

      Any copyright is dedicated to the Public Domain.

      http://creativecommons.org/publicdomain/zero/1.0/

 -->

 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">

   <title>Testcase for objectBoundingBox with fePointLight</title>

   <!-- From https://bugzilla.mozilla.org/show_bug.cgi?id=544742 -->

   <defs>

     <filter id="light" primitiveUnits="objectBoundingBox">

       <feSpecularLighting lighting-color="blue" surfaceScale="5" specularConstant="10" specularExponent="6">

         <!-- Note: for z  the scalefactor is  31,622776601683793319988935444327

                      sqrt(bbox.width*bbox.width + bbox.height*bbox.height)/sqrt(2) -->

         <fePointLight x="0.75" y="1.5" z="-0.15811388300841896659994467722167"/>

       </feSpecularLighting>

       <feComposite operator="in" in2="SourceGraphic"/>

     </filter>

   </defs>

   <rect x="20" y="20" width="40" height="20" filter="url(#light)" fill="black" stroke="none" />

 </svg>