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

chrome/browser/resources/md_history/history_item.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://history/browser_service.html">
@@ skipping 86 matching lines @@
       #domain {
         -webkit-margin-start: 16px;
         color: var(--secondary-text-color);
         flex-shrink: 0;
       }
 
       #menu-button {
         -webkit-margin-end: 12px;
       }
 
-      #bookmark-star {
+      #star-container {
         -webkit-margin-end: 4px;
         -webkit-margin-start: 12px;
-        color: rgb(68, 136, 255);
-        height: 32px;
-        visibility: hidden;
         width: 32px;
       }
 
+      #bookmark-star {
+        color: rgb(68, 136, 255);
+        height: 32px;
+        width: 32px;
+      }
+
       #bookmark-star iron-icon {
         height: 16px;
         width: 16px;
       }
 
-      :host([starred]) #bookmark-star {
-        visibility: visible;
-      }
-
       #time-gap-separator {
         -webkit-border-start: 1px solid #888;
         -webkit-margin-start: 77px;
         height: 15px;
       }
     </style>
 
     <div id="sizing-container">
       <div id="main-container">
         <div id="date-accessed" class="card-title">
           [[cardTitle_(numberOfItems, item.dateRelativeDay, searchTerm)]]
         </div>
         <div id="item-container">
           <paper-checkbox id="checkbox" on-tap="onCheckboxSelected_"
               checked="{{selected}}" disabled="[[selectionNotAllowed_()]]">
           </paper-checkbox>
           <span id="time-accessed">[[item.readableTimestamp]]</span>
           <div class="website-icon" id="icon"></div>
           <div id="title-and-domain">
             <a href="[[item.url]]" id="title" class="website-title">
               <history-searched-label title="[[cropItemTitle_(item.title)]]"
                   search-term="[[searchTerm]]"></history-searched-label>
             </a>
             <span id="domain">[[item.domain]]</span>
           </div>
-          <button is="paper-icon-button-light" id="bookmark-star"
-              title="$i18n{removeBookmark}" on-tap="onRemoveBookmarkTap_">
-            <iron-icon icon="cr:star"></iron-icon>
-          </button>
+          <div id="star-container">
+            <template is="dom-if" if="[[item.starred]]">
+              <button is="paper-icon-button-light" id="bookmark-star"
+                  title="$i18n{removeBookmark}" on-tap="onRemoveBookmarkTap_">
+                <iron-icon icon="cr:star"></iron-icon>
+              </button>
+            </template>
+          </div>
           <button is="paper-icon-button-light" id="menu-button"
               class="icon-button" title="$i18n{moreActionsButton}"
               on-tap="onMenuButtonTap_">
             <iron-icon icon="cr:more-vert"></iron-icon>
           </button>
         </div>
-        <template is="dom-if" if="[[hasTimeGap]]">
-          <div id="time-gap-separator"></div>
-        </template>
+        <div id="time-gap-separator" hidden="[[!hasTimeGap]]"></div>
       </div>
     </div>
   </template>
   <script src="chrome://history/history_item.js"></script>
 </dom-module>