<!DOCTYPE html> <html class="reftest-wait"> <head> </head> <body> <div id="host"></div> <script> var host = document.getElementById("host"); var root = host.createShadowRoot(); root.innerHTML = 'a <content></content> c'; function tweak() { var span = document.createElement("span"); span.innerHTML = "b"; // Span should be distributed to insertion point between 'a' and 'c'. host.appendChild(span); document.documentElement.removeAttribute("class"); } window.addEventListener("MozReftestInvalidate", tweak, false); </script> </body> </html>