MD Settings: Remove some ES6 leftovers from CrOS code that break uglify.

chrome/browser/resources/settings/internet_page/internet_page.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview
  * 'settings-internet-page' is the settings page containing internet
  * settings.
  */
 Polymer({
@@ skipping 218 matching lines @@
    * @private
    */
   onExtensionDisabled_: function(extension) {
     this.onExtensionRemoved_(extension.id);
   },
 
   /**
    * @param {!chrome.networkingPrivate.GlobalPolicy} globalPolicy
    * @return {boolean}
    */
-  allowAddConnection_(globalPolicy) {
+  allowAddConnection_: function(globalPolicy) {
     return !globalPolicy.AllowOnlyPolicyNetworksToConnect;
   },
 
   /**
    * @param {!chrome.networkingPrivate.ThirdPartyVPNProperties} provider
    * @return {string}
    */
   getAddThirdParrtyVpnLabel_: function(provider) {
     return this.i18n('internetAddThirdPartyVPN', provider.ProviderName);
   }
 });