>>290
あー失礼。最後でちょっと手抜きし過ぎた
こっちが本当の正解(たぶん)

var divs = document.getElementsByTagName("div");
for(var i = 0, div; div = divs[i]; i++){
  var position = div.style.position || document.defaultView.getComputedStyle(div,"").getPropertyValue("position");
  if(position == "fixed") div.style.position = "static";
}