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

chrome/browser/resources/settings/internet_page/network_proxy.html

 <link rel="import" href="chrome://resources/html/polymer.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-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input-container.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_onc_types.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_network_behavior.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_network_indicator.html">
 <link rel="import" href="internet_shared_css.html">
 <link rel="import" href="network_property_list.html">
 <link rel="import" href="network_proxy_input.html">
 <link rel="import" href="network_proxy_exclusions.html">
 
 <dom-module id="network-proxy">
   <template>
-    <style include="internet-shared">
+    <style include="iron-flex internet-shared">
       cr-policy-network-indicator {
         -webkit-margin-end: 10px;
       }
 
       network-proxy-input {
         margin-bottom: 10px;
       }
 
       #proxyDiv paper-checkbox {
         padding: 10px 0;
@@ skipping 100 matching lines @@
           </paper-input-container>
           <paper-button on-tap="onAddProxyExclusionTap_">
             Add Exception
           </paper-button>
         </div>
       </div>
     </div>
   </template>
   <script src="network_proxy.js"></script>
 </dom-module>