diff --git a/dom/traversal/TreeWalker-acceptNode-filter.html b/dom/traversal/TreeWalker-acceptNode-filter.html
new file mode 100644
index 00000000000000..1bd28f3b885abc
--- /dev/null
+++ b/dom/traversal/TreeWalker-acceptNode-filter.html
@@ -0,0 +1,160 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/acceptNode-filter.js
+-->
+<head>
+<title>TreeWalker: acceptNode-filter</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test JS objects as NodeFilters</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    //testElement.innerHTML='<div id="A1"><div id="B1"></div><div id="B2"></div></div>';
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div");
+    a1.id = "A1";
+    var b1 = document.createElement("div");
+    b1.id = "B1";
+    var b2 = document.createElement("div");
+    b2.id = "B2";
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2);
+});
+
+test(function()
+{
+    function filter(node)
+    {
+        if (node.id == "B1")
+            return /*NodeFilter.*/FILTER_SKIP;
+        return /*NodeFilter.*/FILTER_ACCEPT;
+    }
+
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.currentNode, { type: Element, id: 'B2' });
+}, 'Testing with raw function filter');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, {
+        acceptNode : function(node) {
+            if (node.id == "B1")
+                return /*NodeFilter.*/FILTER_SKIP;
+            return /*NodeFilter.*/FILTER_ACCEPT;
+        }
+    });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.currentNode, { type: Element, id: 'B2' });
+}, 'Testing with object filter');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, null);
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B1' });
+    assert_node(walker.currentNode, { type: Element, id: 'B1' });
+}, 'Testing with null filter');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, undefined);
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B1' });
+    assert_node(walker.currentNode, { type: Element, id: 'B1' });
+}, 'Testing with undefined filter');
+
+// XXX Servo breaks the test when a callback isn't callable
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, {});
+    assert_throws(null, function () { walker.firstChild(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_throws(null, function () { walker.nextNode(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+}, 'Testing with object lacking acceptNode property');
+
+// XXX Servo breaks the test when a callback isn't callable
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, { acceptNode: "foo" });
+    assert_throws(null, function () { walker.firstChild(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_throws(null, function () { walker.nextNode(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+}, 'Testing with object with non-function acceptNode property');
+
+test(function()
+{
+    var filter = function() { return /*NodeFilter.*/FILTER_ACCEPT; };
+    filter.acceptNode = function(node) { return /*NodeFilter.*/FILTER_SKIP; };
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B1' });
+}, 'Testing with function having acceptNode function');
+
+test(function()
+{
+    var filter = {
+        acceptNode: function(node) {
+            return /*NodeFilter.*/FILTER_ACCEPT;
+        }
+    };
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+}, 'Testing acceptNode callee');
+
+// XXX Looks like Servo is doing something wrong when a callback function throws
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT,
+                                           function(node) {
+                                               throw('filter exception');
+                                               return /*NodeFilter.*/FILTER_ACCEPT;
+                                           });
+    assert_throws(null, function () { walker.firstChild(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_throws(null, function () { walker.nextNode(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+}, 'Testing with filter function that throws');
+
+// XXX Looks like Servo is doing something wrong when a callback function throws
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT,
+                                           {
+                                               acceptNode : function(node) {
+                                                   throw('filter exception');
+                                                   return /*NodeFilter.*/FILTER_ACCEPT;
+                                               }
+                                           });
+    assert_throws(null, function () { walker.firstChild(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_throws(null, function () { walker.nextNode(); });
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+}, 'Testing with filter object that throws');
+
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-basic.html b/dom/traversal/TreeWalker-basic.html
new file mode 100644
index 00000000000000..0720c7c1c6ad88
--- /dev/null
+++ b/dom/traversal/TreeWalker-basic.html
@@ -0,0 +1,146 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html
+-->
+<head>
+<title>TreeWalker: Basic test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>This test checks the basic functionality of TreeWalker.</p>
+<script>
+function createSampleDOM()
+{
+    // Tree structure:
+    //             #a
+    //             |
+    //        +----+----+
+    //        |         |
+    //       "b"        #c
+    //                  |
+    //             +----+----+
+    //             |         |
+    //            #d      <!--j-->
+    //             |
+    //        +----+----+
+    //        |    |    |
+    //       "e"  #f   "i"
+    //             |
+    //          +--+--+
+    //          |     |
+    //         "g" <!--h-->
+    var div = document.createElement('div');
+    div.id = 'a';
+    // div.innerHTML = 'b<div id="c"><div id="d">e<span id="f">g<!--h--></span>i</div><!--j--></div>';
+
+    div.appendChild(document.createTextNode("b"));
+
+    var c = document.createElement("div");
+    c.id = 'c';
+    div.appendChild(c);
+
+    var d = document.createElement("div");
+    d.id = 'd';
+    c.appendChild(d);
+
+    var e = document.createTextNode("e");
+    d.appendChild(e);
+
+    var f = document.createElement("span");
+    f.id = 'f';
+    d.appendChild(f);
+
+    var g = document.createTextNode("g");
+    f.appendChild(g);
+
+    var h = document.createComment("h");
+    f.appendChild(h);
+
+    var i = document.createTextNode("i");
+    d.appendChild(i);
+
+    var j = document.createComment("j");
+    c.appendChild(j);
+
+    return div;
+}
+
+function check_walker(walker, root)
+{
+    assert_equals(walker.toString(), '[object TreeWalker]');
+    assert_equals(walker.root, root);
+    assert_equals(walker.whatToShow, 0xFFFFFFFF);
+    assert_equals(walker.filter, null);
+    assert_equals(walker.currentNode, root);
+    assert_readonly(walker, 'root');
+    assert_readonly(walker, 'whatToShow');
+    assert_readonly(walker, 'filter');
+}
+
+test(function ()
+{
+    var root = createSampleDOM();
+    var walker = document.createTreeWalker(root);
+    check_walker(walker, root);
+}, 'Construct a TreeWalker by document.createTreeWalker(root).');
+
+test(function ()
+{
+    var root = createSampleDOM();
+    var walker = document.createTreeWalker(root, undefined, undefined);
+    check_walker(walker, root);
+}, 'Construct a TreeWalker by document.createTreeWalker(root, undefined, undefined).');
+
+test(function ()
+{
+    assert_throws(new TypeError(), function () { document.createTreeWalker(); });
+    assert_throws(new TypeError(), function () { document.createTreeWalker(null); });
+    assert_throws(new TypeError(), function () { document.createTreeWalker(undefined); });
+    assert_throws(new TypeError(), function () { document.createTreeWalker(new Object()); });
+    assert_throws(new TypeError(), function () { document.createTreeWalker(1); });
+}, 'Give an invalid root node to document.createTreeWalker().');
+
+test(function ()
+{
+    var root = createSampleDOM();
+    var walker = document.createTreeWalker(root);
+    var f = root.lastChild.firstChild.childNodes[1];  // An element node: div#f.
+
+    assert_node(walker.currentNode, { type: Element, id: 'a' });
+    assert_equals(walker.parentNode(), null);
+    assert_node(walker.currentNode, { type: Element, id: 'a' });
+    assert_node(walker.firstChild(), { type: Text, nodeValue: 'b' });
+    assert_node(walker.currentNode, { type: Text, nodeValue: 'b' });
+    assert_node(walker.nextSibling(), { type: Element, id: 'c' });
+    assert_node(walker.currentNode, { type: Element, id: 'c' });
+    assert_node(walker.lastChild(), { type: Comment, nodeValue: 'j' });
+    assert_node(walker.currentNode, { type: Comment, nodeValue: 'j' });
+    assert_node(walker.previousSibling(), { type: Element, id: 'd' });
+    assert_node(walker.currentNode, { type: Element, id: 'd' });
+    assert_node(walker.nextNode(), { type: Text, nodeValue: 'e' });
+    assert_node(walker.currentNode, { type: Text, nodeValue: 'e' });
+    assert_node(walker.parentNode(), { type: Element, id: 'd' });
+    assert_node(walker.currentNode, { type: Element, id: 'd' });
+    assert_node(walker.previousNode(), { type: Element, id: 'c' });
+    assert_node(walker.currentNode, { type: Element, id: 'c' });
+    assert_equals(walker.nextSibling(), null);
+    assert_node(walker.currentNode, { type: Element, id: 'c' });
+    walker.currentNode = f;
+    assert_equals(walker.currentNode, f);
+}, 'Walk over nodes.');
+
+test(function() {
+    var treeWalker = document.createTreeWalker(document.body, 42, null);
+    assert_equals(treeWalker.root, document.body);
+    assert_equals(treeWalker.currentNode, document.body);
+    assert_equals(treeWalker.whatToShow, 42);
+    assert_equals(treeWalker.filter, null);
+}, "Optional arguments to createTreeWalker should be optional (3 passed, null).");
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-currentNode.html b/dom/traversal/TreeWalker-currentNode.html
new file mode 100644
index 00000000000000..dc6a1e28258349
--- /dev/null
+++ b/dom/traversal/TreeWalker-currentNode.html
@@ -0,0 +1,74 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/resources/TreeWalker-currentNode.js
+-->
+<head>
+<title>TreeWalker: currentNode</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<div id='parent'>
+<div id='subTree'><p>Lorem ipsum <span>dolor <b>sit</b> amet</span>, consectetur <i>adipisicing</i> elit, sed do eiusmod <tt>tempor <b><i>incididunt ut</i> labore</b> et dolore magna</tt> aliqua.</p></div>
+</div>
+<p>Test TreeWalker currentNode functionality</p>
+<script>
+// var subTree = document.createElement('div');
+// subTree.innerHTML = "<p>Lorem ipsum <span>dolor <b>sit</b> amet</span>, consectetur <i>adipisicing</i> elit, sed do eiusmod <tt>tempor <b><i>incididunt ut</i> labore</b> et dolore magna</tt> aliqua.</p>"
+// document.body.appendChild(subTree);
+var subTree = document.getElementById("subTree");
+
+var all = function(node) { return true; }
+
+test(function()
+{
+    var w = document.createTreeWalker(subTree, /*NodeFilter.*/SHOW_ELEMENT, all);
+    assert_node(w.currentNode, { type: Element, id: 'subTree' });
+    assert_equals(w.parentNode(), null);
+    assert_node(w.currentNode, { type: Element, id: 'subTree' });
+}, "Test that TreeWalker.parent() doesn't set the currentNode to a node not under the root.");
+
+test(function()
+{
+    var w = document.createTreeWalker(subTree,
+                                      /*NodeFilter.*/SHOW_ELEMENT
+                                      | /*NodeFilter.*/SHOW_COMMENT,
+                                      all);
+    w.currentNode = document.documentElement;
+    assert_equals(w.parentNode(), null);
+    assert_equals(w.currentNode, document.documentElement);
+    w.currentNode = document.documentElement;
+    assert_equals(w.nextNode(), document.documentElement.firstChild);
+    assert_equals(w.currentNode, document.documentElement.firstChild);
+    w.currentNode = document.documentElement;
+    assert_equals(w.previousNode(), null);
+    assert_equals(w.currentNode, document.documentElement);
+    w.currentNode = document.documentElement;
+    assert_equals(w.firstChild(), document.documentElement.firstChild);
+    assert_equals(w.currentNode, document.documentElement.firstChild);
+    w.currentNode = document.documentElement;
+    assert_equals(w.lastChild(), document.documentElement.lastChild);
+    assert_equals(w.currentNode, document.documentElement.lastChild);
+    w.currentNode = document.documentElement;
+    assert_equals(w.nextSibling(), null);
+    assert_equals(w.currentNode, document.documentElement);
+    w.currentNode = document.documentElement;
+    assert_equals(w.previousSibling(), null);
+    assert_equals(w.currentNode, document.documentElement);
+}, "Test that we handle setting the currentNode to arbitrary nodes not under the root element.");
+
+test(function()
+{
+    var w = document.createTreeWalker(subTree, /*NodeFilter.*/SHOW_ELEMENT, all);
+    w.currentNode = subTree.previousSibling;
+    assert_equals(w.nextNode(), subTree);
+    w.currentNode = document.getElementById("parent");
+    assert_equals(w.firstChild(), subTree);
+}, "Test how we handle the case when the traversed to node is within the root, but the currentElement is not.");
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-previousNodeLastChildReject.html b/dom/traversal/TreeWalker-previousNodeLastChildReject.html
new file mode 100644
index 00000000000000..b1ae7787a940bb
--- /dev/null
+++ b/dom/traversal/TreeWalker-previousNodeLastChildReject.html
@@ -0,0 +1,88 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/previousNodeLastChildReject.js
+-->
+<head>
+<title>TreeWalker: previousNodeLastChildReject</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test that previousNode properly respects the filter.</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    // testElement.innerHTML='<div id="A1"><div id="B1"><div id="C1"></div><div id="C2"><div id="D1"></div><div id="D2"></div></div></div><div id="B2"><div id="C3"></div><div id="C4"></div></div></div>';
+    // testElement.innerHTML='
+    // <div id="A1">
+    //   <div id="B1">
+    //     <div id="C1">
+    //     </div>
+    //     <div id="C2">
+    //       <div id="D1">
+    //       </div>
+    //       <div id="D2">
+    //       </div>
+    //     </div>
+    //   </div>
+    //   <div id="B2">
+    //     <div id="C3">
+    //     </div>
+    //     <div id="C4">
+    //     </div>
+    //   </div>
+    // </div>';
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div"); a1.id = "A1";
+    var b1 = document.createElement("div"); b1.id = "B1";
+    var b2 = document.createElement("div"); b2.id = "B2";
+    var c1 = document.createElement("div"); c1.id = "C1";
+    var c2 = document.createElement("div"); c2.id = "C2";
+    var c3 = document.createElement("div"); c3.id = "C3";
+    var c4 = document.createElement("div"); c4.id = "C4";
+    var d1 = document.createElement("div"); d1.id = "D1";
+    var d2 = document.createElement("div"); d2.id = "D2";
+
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2);
+    b1.appendChild(c1);
+    b1.appendChild(c2);
+    b2.appendChild(c3);
+    b2.appendChild(c4);
+    c2.appendChild(d1);
+    c2.appendChild(d2);
+});
+
+test(function()
+{
+    function filter(node)
+    {
+        if (node.id == "C2")
+            return /*NodeFilter.*/FILTER_REJECT;
+        return /*NodeFilter.*/FILTER_ACCEPT;
+    }
+
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B1' });
+    assert_node(walker.currentNode, { type: Element, id: 'B1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'C1' });
+    assert_node(walker.currentNode, { type: Element, id: 'C1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.currentNode, { type: Element, id: 'B2' });
+    assert_node(walker.previousNode(), { type: Element, id: 'C1' });
+    assert_node(walker.currentNode, { type: Element, id: 'C1' });
+}, 'Test that previousNode properly respects the filter.');
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-previousSiblingLastChildSkip.html b/dom/traversal/TreeWalker-previousSiblingLastChildSkip.html
new file mode 100644
index 00000000000000..b7c8fadde74b71
--- /dev/null
+++ b/dom/traversal/TreeWalker-previousSiblingLastChildSkip.html
@@ -0,0 +1,92 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/previousSiblingLastChildSkip.js
+-->
+<head>
+<title>TreeWalker: previousSiblingLastChildSkip</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test that previousSibling properly respects the filter.</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    // testElement.innerHTML='<div id="A1"><div id="B1"><div id="C1"></div><div id="C2"><div id="D1"></div><div id="D2"></div></div></div><div id="B2"><div id="C3"></div><div id="C4"></div></div></div>';
+    // testElement.innerHTML='
+    // <div id="A1">
+    //   <div id="B1">
+    //     <div id="C1">
+    //     </div>
+    //     <div id="C2">
+    //       <div id="D1">
+    //       </div>
+    //       <div id="D2">
+    //       </div>
+    //     </div>
+    //   </div>
+    //   <div id="B2">
+    //     <div id="C3">
+    //     </div>
+    //     <div id="C4">
+    //     </div>
+    //   </div>
+    // </div>';
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div"); a1.id = "A1";
+    var b1 = document.createElement("div"); b1.id = "B1";
+    var b2 = document.createElement("div"); b2.id = "B2";
+    var c1 = document.createElement("div"); c1.id = "C1";
+    var c2 = document.createElement("div"); c2.id = "C2";
+    var c3 = document.createElement("div"); c3.id = "C3";
+    var c4 = document.createElement("div"); c4.id = "C4";
+    var d1 = document.createElement("div"); d1.id = "D1";
+    var d2 = document.createElement("div"); d2.id = "D2";
+
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2);
+    b1.appendChild(c1);
+    b1.appendChild(c2);
+    b2.appendChild(c3);
+    b2.appendChild(c4);
+    c2.appendChild(d1);
+    c2.appendChild(d2);
+});
+
+test(function()
+{
+    function filter(node)
+    {
+        if (node.id == "B1")
+            return /*NodeFilter.*/FILTER_SKIP;
+        return /*NodeFilter.*/FILTER_ACCEPT;
+    }
+
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.currentNode, { type: Element, id: 'root' });
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.currentNode, { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'C1' });
+    assert_node(walker.currentNode, { type: Element, id: 'C1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'C2' });
+    assert_node(walker.currentNode, { type: Element, id: 'C2' });
+    assert_node(walker.nextNode(), { type: Element, id: 'D1' });
+    assert_node(walker.currentNode, { type: Element, id: 'D1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'D2' });
+    assert_node(walker.currentNode, { type: Element, id: 'D2' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.currentNode, { type: Element, id: 'B2' });
+    assert_node(walker.previousSibling(), { type: Element, id: 'C2' });
+    assert_node(walker.currentNode, { type: Element, id: 'C2' });
+}, 'Test that previousSibling properly respects the filter.');
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-traversal-reject.html b/dom/traversal/TreeWalker-traversal-reject.html
new file mode 100644
index 00000000000000..e04487560b66db
--- /dev/null
+++ b/dom/traversal/TreeWalker-traversal-reject.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/traversal-reject.js
+-->
+<head>
+<title>TreeWalker: traversal-reject</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test TreeWalker with rejection</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    //testElement.innerHTML='<div id="A1">  <div id="B1">  <div id="C1"></div>  </div>  <div id="B2"></div><div id="B3"></div>  </div>';
+    // <div id="A1">
+    //   <div id="B1">
+    //     <div id="C1"></div>
+    //   </div>
+    //   <div id="B2"></div>
+    //   <div id="B3"></div>
+    // </div>
+
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div"); a1.id = "A1";
+    var b1 = document.createElement("div"); b1.id = "B1";
+    var b2 = document.createElement("div"); b2.id = "B2";
+    var b3 = document.createElement("div"); b3.id = "B3";
+    var c1 = document.createElement("div"); c1.id = "C1";
+
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2);
+    a1.appendChild(b3);
+    b1.appendChild(c1);
+});
+
+var rejectB1Filter = {
+  acceptNode: function(node) {
+    if (node.id == 'B1')
+      return /*NodeFilter.*/FILTER_REJECT;
+
+    return /*NodeFilter.*/FILTER_ACCEPT;
+  }
+}
+
+var skipB2Filter = {
+  acceptNode: function(node) {
+    if (node.id == 'B2')
+      return /*NodeFilter.*/FILTER_SKIP;
+
+    return /*NodeFilter.*/FILTER_ACCEPT;
+  }
+}
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, rejectB1Filter);
+    assert_node(walker.nextNode(), { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B3' });
+}, 'Testing nextNode');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, rejectB1Filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.firstChild(), { type: Element, id: 'B2' });
+}, 'Testing firstChild');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB2Filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.firstChild(), { type: Element, id: 'B1' });
+    assert_node(walker.nextSibling(), { type: Element, id: 'B3' });
+}, 'Testing nextSibling');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, rejectB1Filter);
+    walker.currentNode = testElement.querySelectorAll('#C1')[0];
+    assert_node(walker.parentNode(), { type: Element, id: 'A1' });
+}, 'Testing parentNode');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB2Filter);
+    walker.currentNode = testElement.querySelectorAll('#B3')[0];
+    assert_node(walker.previousSibling(), { type: Element, id: 'B1' });
+}, 'Testing previousSibling');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, rejectB1Filter);
+    walker.currentNode = testElement.querySelectorAll('#B3')[0];
+    assert_node(walker.previousNode(), { type: Element, id: 'B2' });
+    assert_node(walker.previousNode(), { type: Element, id: 'A1' });
+}, 'Testing previousNode');
+
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-traversal-skip-most.html b/dom/traversal/TreeWalker-traversal-skip-most.html
new file mode 100644
index 00000000000000..24250363e3983b
--- /dev/null
+++ b/dom/traversal/TreeWalker-traversal-skip-most.html
@@ -0,0 +1,67 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/traversal-skip-most.js
+-->
+<head>
+<title>TreeWalker: traversal-skip-most</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test TreeWalker with skipping</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    // testElement.innerHTML='<div id="A1"><div id="B1" class="keep"></div><div id="B2">this text matters</div><div id="B3" class="keep"></div></div>';
+    // <div id="A1">
+    //   <div id="B1" class="keep"></div>
+    //   <div id="B2">this text matters</div>
+    //   <div id="B3" class="keep"></div>
+    // </div>
+
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div"); a1.id = "A1";
+    var b1 = document.createElement("div"); b1.id = "B1"; b1.className = "keep";
+    var b2 = document.createElement("div"); b2.id = "B2";
+    var b3 = document.createElement("div"); b3.id = "B3"; b3.className = "keep";
+
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2)
+        .appendChild(document.createTextNode("this text matters"));
+    a1.appendChild(b3);
+});
+
+var filter = {
+  acceptNode: function(node) {
+    if (node.className == 'keep')
+      return /*NodeFilter.*/FILTER_ACCEPT;
+
+    return /*NodeFilter.*/FILTER_SKIP;
+  }
+}
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'B1' });
+    assert_node(walker.nextSibling(), { type: Element, id: 'B3' });
+}, 'Testing nextSibling');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, filter);
+    walker.currentNode = testElement.querySelectorAll('#B3')[0];
+    assert_node(walker.previousSibling(), { type: Element, id: 'B1' });
+}, 'Testing previousSibling');
+
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-traversal-skip.html b/dom/traversal/TreeWalker-traversal-skip.html
new file mode 100644
index 00000000000000..1c71f6b284d019
--- /dev/null
+++ b/dom/traversal/TreeWalker-traversal-skip.html
@@ -0,0 +1,112 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://mxr.mozilla.org/chromium/source/src/third_party/WebKit/LayoutTests/fast/dom/TreeWalker/script-tests/traversal-skip.js
+-->
+<head>
+<title>TreeWalker: traversal-skip</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>Test TreeWalker with skipping</p>
+<script>
+var testElement;
+setup(function() {
+    testElement = document.createElement("div");
+    testElement.id = 'root';
+    // testElement.innerHTML='<div id="A1">  <div id="B1">  <div id="C1"></div>  </div>  <div id="B2"></div><div id="B3"></div>  </div>';
+    // <div id="A1">
+    //   <div id="B1">
+    //     <div id="C1"></div>
+    //   </div>
+    //   <div id="B2"></div>
+    //   <div id="B3"></div>
+    // </div>
+
+
+    // XXX for Servo, build the tree without using innerHTML
+    var a1 = document.createElement("div"); a1.id = "A1";
+    var b1 = document.createElement("div"); b1.id = "B1";
+    var b2 = document.createElement("div"); b2.id = "B2";
+    var b3 = document.createElement("div"); b3.id = "B3";
+    var c1 = document.createElement("div"); c1.id = "C1";
+
+    testElement.appendChild(a1);
+    a1.appendChild(b1);
+    a1.appendChild(b2);
+    a1.appendChild(b3);
+    b1.appendChild(c1);
+});
+
+var skipB1Filter = {
+  acceptNode: function(node) {
+    if (node.id == 'B1')
+      return /*NodeFilter.*/FILTER_SKIP;
+
+    return /*NodeFilter.*/FILTER_ACCEPT;
+  }
+}
+
+var skipB2Filter = {
+  acceptNode: function(node) {
+    if (node.id == 'B2')
+      return /*NodeFilter.*/FILTER_SKIP;
+
+    return /*NodeFilter.*/FILTER_ACCEPT;
+  }
+}
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB1Filter);
+    assert_node(walker.nextNode(), { type: Element, id: 'A1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'C1' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B2' });
+    assert_node(walker.nextNode(), { type: Element, id: 'B3' });
+}, 'Testing nextNode');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB1Filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.firstChild(), { type: Element, id: 'C1' });
+}, 'Testing firstChild');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB2Filter);
+    assert_node(walker.firstChild(), { type: Element, id: 'A1' });
+    assert_node(walker.firstChild(), { type: Element, id: 'B1' });
+    assert_node(walker.nextSibling(), { type: Element, id: 'B3' });
+}, 'Testing nextSibling');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB1Filter);
+    walker.currentNode = testElement.querySelectorAll('#C1')[0];
+    assert_node(walker.parentNode(), { type: Element, id: 'A1' });
+}, 'Testing parentNode');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB2Filter);
+    walker.currentNode = testElement.querySelectorAll('#B3')[0];
+    assert_node(walker.previousSibling(), { type: Element, id: 'B1' });
+}, 'Testing previousSibling');
+
+test(function()
+{
+    var walker = document.createTreeWalker(testElement, /*NodeFilter.*/SHOW_ELEMENT, skipB1Filter);
+    walker.currentNode = testElement.querySelectorAll('#B3')[0];
+    assert_node(walker.previousNode(), { type: Element, id: 'B2' });
+    assert_node(walker.previousNode(), { type: Element, id: 'C1' });
+    assert_node(walker.previousNode(), { type: Element, id: 'A1' });
+}, 'Testing previousNode');
+
+</script>
+</body>
+</html>
diff --git a/dom/traversal/TreeWalker-walking-outside-a-tree.html b/dom/traversal/TreeWalker-walking-outside-a-tree.html
new file mode 100644
index 00000000000000..4efae976cac116
--- /dev/null
+++ b/dom/traversal/TreeWalker-walking-outside-a-tree.html
@@ -0,0 +1,41 @@
+<!DOCTYPE html>
+<html>
+<!--
+Test adapted from https://github.com/operasoftware/presto-testo/blob/master/core/standards/acid3/individual/006a.html
+-->
+<head>
+<title>TreeWalker: walking-outside-a-tree</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="traversal-support.js"></script>
+<link rel="stylesheet" href="/resources/testharness.css">
+<div id=log></div>
+</head>
+<body>
+<p>[Acid3 - Test 006a] walking outside a tree</p>
+<script>
+test(function () {
+    // test 6: walking outside a tree
+    var doc = document.createElement("div");
+    var head = document.createElement('head');
+    var title = document.createElement('title');
+    var body = document.createElement('body');
+    var p = document.createElement('p');
+    doc.appendChild(head);
+    head.appendChild(title);
+    doc.appendChild(body);
+    body.appendChild(p);
+
+    var w = document.createTreeWalker(body, 0xFFFFFFFF, null);
+    doc.removeChild(body);
+    assert_equals(w.lastChild(), p, "TreeWalker failed after removing the current node from the tree");
+    doc.appendChild(p);
+    assert_equals(w.previousNode(), title, "failed to handle regrafting correctly");
+    p.appendChild(body);
+    assert_equals(w.nextNode(), p, "couldn't retrace steps");
+    assert_equals(w.nextNode(), body, "couldn't step back into root");
+    assert_equals(w.previousNode(), null, "root didn't retake its rootish position");
+}, "walking outside a tree");
+</script>
+</body>
+</html>
diff --git a/dom/traversal/traversal-support.js b/dom/traversal/traversal-support.js
new file mode 100644
index 00000000000000..b21428d5419386
--- /dev/null
+++ b/dom/traversal/traversal-support.js
@@ -0,0 +1,28 @@
+// |expected| should be an object indicating the expected type of node.
+function assert_node(actual, expected)
+{
+    assert_true(actual instanceof expected.type,
+                'Node type mismatch: actual = ' + actual.nodeType + ', expected = ' + expected.nodeType);
+    if (typeof(expected.id) !== 'undefined')
+        assert_equals(actual.id, expected.id);
+    if (typeof(expected.nodeValue) !== 'undefined')
+        assert_equals(actual.nodeValue, expected.nodeValue);
+}
+
+// XXX Servo doesn't have these constants in NodeFilter yet
+var FILTER_ACCEPT = 1;
+var FILTER_REJECT = 2;
+var FILTER_SKIP = 3;
+var SHOW_ALL = 0xFFFFFFFF;
+var SHOW_ELEMENT = 0x1;
+var SHOW_ATTRIBUTE = 0x2;
+var SHOW_TEXT = 0x4;
+var SHOW_CDATA_SECTION = 0x8;
+var SHOW_ENTITY_REFERENCE = 0x10;
+var SHOW_ENTITY = 0x20;
+var SHOW_PROCESSING_INSTRUCTION = 0x40;
+var SHOW_COMMENT = 0x80;
+var SHOW_DOCUMENT = 0x100;
+var SHOW_DOCUMENT_TYPE = 0x200;
+var SHOW_DOCUMENT_FRAGMENT = 0x400;
+var SHOW_NOTATION = 0x800;
