Replace deprecated iron-flex-layout/classes with iron-flex-layout-class in MD Settings

chrome/browser/resources/settings/site_settings/site_list.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/html/web_ui_listener_behavior.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-flex-layout/iron-flex-layout-classes.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-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-submenu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu-button/paper-menu-button.html">
 <link rel="import" href="/i18n_setup.html">
 <link rel="import" href="/icons.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_shared_css.html">
 <link rel="import" href="/site_settings/add_site_dialog.html">
 <link rel="import" href="/site_settings/constants.html">
 <link rel="import" href="/site_settings/site_settings_behavior.html">
 <link rel="import" href="/site_settings/site_settings_prefs_browser_proxy.html">
 
 <dom-module id="settings-site-list">
   <template>
-    <style include="settings-shared">
+    <style include="iron-flex settings-shared">
       paper-menu-button {
         left: 8px;
         margin: 0;
         padding: 0;
         right: 8px;
       }
 
       .button-container {
         -webkit-margin-start: -4px;
       }
@@ skipping 73 matching lines @@
                 class="primary-button no-upper">
               $i18n{addSiteLink}
             </paper-button>
           </div>
         </template>
       </div>
     </paper-submenu>
   </template>
   <script src="site_list.js"></script>
 </dom-module>