MD Bookmarks: Update URL router to work in new data binding system

chrome/test/data/webui/md_bookmarks/test_util.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Replace the current body of the test with a new element.
  * @param {Element} element
  */
 function replaceBody(element) {
   PolymerTest.clearBody();
+
+  window.history.replaceState({}, '', '/');
+
   document.body.appendChild(element);
 }
 
 /**
  * Convert a list of top-level bookmark nodes into a normalized lookup table of
  * nodes.
  * @param {...BookmarkTreeNode} nodes
  */
 function testTree(nodes) {
   return bookmarks.util.normalizeNodes(
@@ skipping 74 matching lines @@
 
   if (config) {
     for (var key in config)
       props[key] = config[key];
   }
 
   element.dispatchEvent(new MouseEvent('mousedown', props));
   element.dispatchEvent(new MouseEvent('mouseup', props));
   element.dispatchEvent(new MouseEvent('click', props));
 }