[MD Bookmarks] Add keyboard navigation to sidebar.

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

Index: chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
diff --git a/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js b/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
index 8d88cd526412393cc7e7cb2985a15b526c8eecab..f8b960d84bceeeaa1cc704da78ab3f324db2f1d8 100644
--- a/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
+++ b/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
@@ -5,7 +5,7 @@
 suite('drag and drop', function() {
   var app;
   var list;
-  var sidebar;
+  var rootFolderNode;
   var store;
   var dndManager;
   var draggedIds;
@@ -18,16 +18,7 @@ suite('drag and drop', function() {
   };
 
   function getFolderNode(id) {
-    var nodes = [sidebar];
-    var node;
-    while (nodes.length) {
-      node = nodes.pop();
-      if (node.itemId == id)
-        return node;
-
-      node.root.querySelectorAll('bookmarks-folder-node')
-          .forEach((x) => {nodes.unshift(x)});
-    }
+    return findFolderNode(rootFolderNode, id);
   }
 
   function getListItem(id) {
@@ -107,7 +98,7 @@ suite('drag and drop', function() {
     app = document.createElement('bookmarks-app');
     replaceBody(app);
     list = app.$$('bookmarks-list');
-    sidebar = app.$$('bookmarks-folder-node');
+    rootFolderNode = app.$$('bookmarks-folder-node');
     dndManager = app.dndManager_;
     dndManager.dropIndicator_.disableTimeoutForTesting();
     Polymer.dom.flush();