MD Extensions: convert last i18n-* attributes to $i18n{}

chrome/browser/resources/md_extensions/sidebar.html

 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/hardware-icons.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-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-item/paper-item.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
 <link rel="import" href="chrome://extensions/icons.html">
 
 <dom-module id="extensions-sidebar">
   <template>
     <paper-menu id="section-menu" selected="0">
       <paper-item class="section-menu-item" id="sections-extensions"
           on-tap="onExtensionsTap_">
         <iron-icon icon="extension"></iron-icon>
-        <span i18n-content="sidebarExtensions"></span>
+        <span>$i18n{sidebarExtensions}</span>
       </paper-item>
       <paper-item class="section-menu-item" id="sections-apps"
           on-tap="onAppsTap_">
         <iron-icon icon="apps"></iron-icon>
-        <span i18n-content="sidebarApps"></span>
+        <span>$i18n{sidebarApps}</span>
       </paper-item>
     </paper-menu>
     <a class="section-item" id="more-extensions" target="_blank"
         href="$i18n{getMoreExtensionsUrl}">
       <paper-item>
         <iron-icon icon="extensions-icons:store"></iron-icon>
         <span>$i18n{getMoreExtensions}</span>
       </paper-item>
     </a>
     <paper-item class="section-item" id="keyboard-shortcuts"
@@ skipping 20 matching lines @@
         <paper-item class="section-item" id="update-now"
             on-tap="onUpdateNowTap_">
           <span>$i18n{sidebarUpdateNow}</span>
         </paper-item>
       </template>
     </div>
   </template>
   <link rel="import" type="css" href="chrome://extensions/sidebar.css">
   <script src="chrome://extensions/sidebar.js"></script>
 </dom-module>