MD History: Improve dom-if usage in history-item

chrome/browser/resources/md_history/history_item.js

 // Copyright 2015 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('md_history', function() {
   var HistoryItem = Polymer({
     is: 'history-item',
 
     properties: {
       // Underlying HistoryEntry data for this item. Contains read-only fields
       // from the history backend, as well as fields computed by history-list.
       item: {type: Object, observer: 'showIcon_'},
 
-      // True if the website is a bookmarked page.
-      starred: {type: Boolean, reflectToAttribute: true},
-
       // Search term used to obtain this history-item.
       searchTerm: {type: String},
 
       selected: {type: Boolean, notify: true},
 
       isFirstItem: {type: Boolean, reflectToAttribute: true},
 
       isCardStart: {type: Boolean, reflectToAttribute: true},
 
       isCardEnd: {type: Boolean, reflectToAttribute: true},
@@ skipping 16 matching lines @@
       this.fire('history-checkbox-select', {
         countAddition: this.$.checkbox.checked ? 1 : -1
       });
     },
 
     /**
      * Remove bookmark of current item when bookmark-star is clicked.
      * @private
      */
     onRemoveBookmarkTap_: function() {
-      if (this.$['bookmark-star'] == this.root.activeElement)
+      if (!this.item.starred)
+        return;
+
+      if (this.$$('#bookmark-star') == this.root.activeElement)
         this.$['menu-button'].focus();
 
       md_history.BrowserService.getInstance()
         .removeBookmark(this.item.url);
       this.fire('remove-bookmark-stars', this.item.url);
     },
 
     /**
      * Fires a custom event when the menu button is clicked. Sends the details
      * of the history item and where the menu should appear.
@@ skipping 67 matching lines @@
 
     if (searchedTerm)
       return currentItem.dateShort != nextItem.dateShort;
 
     return currentItem.time - nextItem.time > BROWSING_GAP_TIME &&
         currentItem.dateRelativeDay == nextItem.dateRelativeDay;
   };
 
   return { HistoryItem: HistoryItem };
 });