Roll closure compiler

ui/webui/resources/js/cr/ui/tree.js

 // Copyright (c) 2012 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.
 
 cr.define('cr.ui', function() {
   // require cr.ui.define
   // require cr.ui.limitInputWidth
 
   /**
    * The number of pixels to indent per level.
    * @type {number}
    * @const
    */
   var INDENT = 20;
 
   /**
    * Returns the computed style for an element.
    * @param {!Element} el The element to get the computed style for.
    * @return {!CSSStyleDeclaration} The computed style.
    */
   function getComputedStyle(el) {
-    return el.ownerDocument.defaultView.getComputedStyle(el);
+    return assert(el.ownerDocument.defaultView.getComputedStyle(el));
   }
 
   /**
    * Helper function that finds the first ancestor tree item.
    * @param {Node} node The node to start searching from.
    * @return {cr.ui.TreeItem} The found tree item or null if not found.
    */
   function findTreeItem(node) {
     while (node && !(node instanceof TreeItem)) {
       node = node.parentNode;
@@ skipping 663 matching lines @@
     if (item.expanded && item.hasChildren) {
       var lastChild = item.items[item.items.length - 1];
       return getLastHelper(lastChild);
     }
     return item;
   }
 
   // Export
   return {Tree: Tree, TreeItem: TreeItem};
 });