walker.js

var anonElements = [];
var walker = Cc["@mozilla.org/inspector/deep-tree-walker;1"].
             createInstance(Ci.inIDeepTreeWalker);
walker.showAnonymousContent = true;
walker.showSubDocuments = false;
walker.showDocumentsAsNodes = false;
walker.init(document.documentElement, NodeFilter.SHOW_ELEMENT);

while (walker.nextNode()) {
  var bindingParent = document.getBindingParent(walker.currentNode);
  if (bindingParent && document.getAnonymousNodes(bindingParent)) {
    anonElements.push(walker.currentNode);
  }
}
anonElements;