MD Downloads: use <iron-list> to render download items

chrome/browser/resources/md_downloads/item.html

 <link rel="import" href="chrome://resources/html/action_link.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/load_time_data.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.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-progress/paper-progress.html">
 <link rel="import" href="chrome://downloads/action_service.html">
 <link rel="import" href="chrome://downloads/constants.html">
-<link rel="import" href="chrome://downloads/throttled_icon_loader.html">
 
 <dom-module id="downloads-item">
   <template>
     <template is="dom-if" if="[[!hideDate]]">
       <h3 id="date">[[computeDate_(hideDate, data.since_string, data.date_string)]]</h3>
     </template>
 
     <div id="content" on-dragstart="onDragStart_"
         class$="[[computeClass_(isActive_, isDangerous_, showProgress_)]]">
       <div id="file-icon-wrapper" class="icon-wrapper">
@@ skipping 78 matching lines @@
       <div id="incognito" i18n-values="title:inIncognito"
           hidden="[[!data.otr]]"></div>
     </div>
 
   </template>
   <link rel="import" type="css" href="chrome://resources/css/action_link.css">
   <link rel="import" type="css" href="chrome://downloads/shared_style.css">
   <link rel="import" type="css" href="chrome://downloads/item.css">
   <script src="chrome://downloads/item.js"></script>
 </dom-module>