diff -r 000000000000 -r 6474c204b198 dom/tests/js/DumpTree.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/tests/js/DumpTree.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,44 @@
+/* -*- Mode: js; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+//
+// travers the html tree and dump out the type of element
+//
+function traverse(node, indent)
+{
+    dump("\n")
+    indent += "  "
+    var type = node.nodeType;
+
+    // if it's an element dump the tag and recurse the children
+    if (type == Node.ELEMENT_NODE) {
+
+        dump(indent + node.tagName)
+
+        // go through the children
+        if (node.hasChildNodes()) {
+            var children = node.childNodes;
+            var length = children.length;
+            var count = 0;
+            while(count < length) {
+                child = children[count]
+                traverse(child, indent)
+                count++
+            }
+        }
+    }
+    // it's just text, no tag, dump "Text"
+    else if (type == Node.TEXT_NODE) {
+        dump(indent + "Text")
+    }
+}
+
+var node = document.documentElement
+
+traverse(node, "")
+dump("\n")
+
+  
\ No newline at end of file