gecko-dev/dom/svg/test/object-delayed-intrinsic-size.sjs

var timer = null;

function handleRequest(request, response)
{
  response.processAsync();

  response.setStatusLine(null, 200, "OK");
  response.setHeader("Content-Type", "image/svg+xml", false);

  // We need some body output or else gecko will not do an initial reflow
  // while waiting for the rest of the document to load:
  response.bodyOutputStream.write("\n", 1);

  timer = Components.classes["@mozilla.org/timer;1"]
                    .createInstance(Components.interfaces.nsITimer);
  timer.initWithCallback(function()
  {
    var body = "<svg xmlns='http://www.w3.org/2000/svg' width='70' height='0'></svg>";
    response.bodyOutputStream.write(body, body.length);
    response.finish();
  }, 1000 /* milliseconds */, Components.interfaces.nsITimer.TYPE_ONE_SHOT);
}