The Tor Browser / file revision

 <svg xmlns="http://www.w3.org/2000/svg" version="1.1">

 <!-- This reference SVG must perform *exactly* the same path construction,

      clipping, and filling operations that PaintBoxShadowInner does for

      the HTML test file. If it doesn't match perfectly, antialiased

      pixels at the curved edges will not agree.

      PaintBoxShadowInner defines both its second (nonrectangular)

      clipping path and its fill path as the even-odd-rule compositions

      of two rectangles, one with nonzero corner radius. It is

      impossible to express "the path consisting of the even-odd-rule

      composition of two |rect| elements" in SVG. This is a minor

      nuisance because we have to write everything out using |path|,

      plus a major nuisance because Gecko uses the same ellipse-to-

      Bezier conversion for rounded rectangles in SVG and HTML, but the

      SVG 'A' operator uses a different one. Therefore we cannot use 'A'.

      The 'C' parameters here were obtained by dumping out the cairo

      operations used to draw the HTML, using cairo-trace. -->

   <defs>

     <clipPath id="outer">

       <rect x="16" y="16" width="240" height="240"/>

     </clipPath>

     <clipPath id="inner">

       <path clip-rule="evenodd"

 	    d="M 248 16

 	       H 24  C 19.58468 16 16 19.58468 16 24

 	       V 248 C 16 252.41532 19.58468 256 24 256

 	       H 248 C 252.41532 256 256 252.41532 256 248

 	       V 24  C 256 19.58468 252.41532 16 248 16 Z

 	       M 48 56 H 272 V 296 H 48 Z"/>

     </clipPath>

   </defs>

   <g clip-path="url(#outer)">

     <path fill="grey" fill-rule="evenodd" clip-path="url(#inner)"

 	  d="M 16 16 H 256 V 256 H 16 Z

 	     M 280 48

 	     H 56  C 51.58468 48 48 51.58468 48 56

 	     V 280 C 48 284.41532 51.58468 288 56 288

 	     H 280 C 284.41532 288 288 284.41532 288 280

 	     V 56  C 288 51.58468 284.41532 48 280 48 Z"/>

   </g>

 </svg>