MD History: Simplify flex layout in <history-list>

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},
 
       hasTimeGap: {type: Boolean},
 
       numberOfItems: {type: Number}
     },
 
     /**
@@ skipping 68 matching lines @@
 
     if (searchedTerm)
       return currentItem.dateShort != nextItem.dateShort;
 
     return currentItem.time - nextItem.time > BROWSING_GAP_TIME &&
         currentItem.dateRelativeDay == nextItem.dateRelativeDay;
   };
 
   return { HistoryItem: HistoryItem };
 });