MD Settings: Remove usage of deprecated iron-flex-layout.html, for CrOS.

chrome/browser/resources/settings/bluetooth_page/bluetooth_device_dialog.html

 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_scrollable_behavior.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-flex-layout/classes/iron-flex-layout.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/iron-list/iron-list.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-input/paper-input.html">
 <link rel="import" href="../bluetooth_page/bluetooth_device_list_item.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <dom-module id="bluetooth-device-dialog">
   <template>
-    <style include="settings-shared">
+    <style include="settings-shared iron-flex">
       #pairing {
         margin-bottom: 10px;
       }
 
       #pairing paper-input {
         text-align: center;
       }
 
       #pinDiv {
         margin-top: 10px;
@@ skipping 106 matching lines @@
         </template>
         <template is="dom-if" if="[[isDialogType_('connectError', dialogId)]]">
           <paper-button  on-tap="close">$i18n{bluetoothDismiss}
           </paper-button>
         </template>
       </div>
     </dialog>
   </template>
   <script src="bluetooth_device_dialog.js"></script>
 </dom-module>