michael@0: var topElements = document.getElementsByClassName("scrollTop");
michael@0: if (!topElements.length) {
michael@0:   topElements = [document.documentElement];
michael@0: }
michael@0: 
michael@0: var failed = false;
michael@0: 
michael@0: function doScroll(d)
michael@0: {
michael@0:   if (failed)
michael@0:     return;
michael@0:   for (var i = 0; i < topElements.length; ++i) {
michael@0:     var e = topElements[i];
michael@0:     e.scrollTop = d;
michael@0:     if (e.scrollTop != d) {
michael@0:       document.documentElement.textContent =
michael@0:           "Scrolling failed on " + e.tagName + " element, " +
michael@0:           "tried to scroll to " + d + ", got " + e.scrollTop +
michael@0:           " (Random number: " + Math.random() + ")";
michael@0:       failed = true;
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: if (document.location.search == '?ref') {
michael@0:   doScroll(20);
michael@0: } else if (document.location.search == '?up') {
michael@0:   doScroll(40);
michael@0:   document.documentElement.setAttribute("class", "reftest-wait");
michael@0:   window.addEventListener("MozReftestInvalidate", function() {
michael@0:     document.documentElement.removeAttribute("class");
michael@0:     doScroll(20);
michael@0:   }, false);
michael@0: } else {
michael@0:   doScroll(1);
michael@0:   document.documentElement.setAttribute("class", "reftest-wait");
michael@0:   window.addEventListener("MozReftestInvalidate", function() {
michael@0:     document.documentElement.removeAttribute("class");
michael@0:     doScroll(20);
michael@0:   }, false);
michael@0: }