Use proper Polymer properties syntax.

Bug: 893934,955194
Change-Id: Ie97de2f2034f2169c5c473a55c7a88388e6ae725
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872056Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712631}

chrome/browser/resources/chromeos/login/oobe_network.js

@@ -21,21 +21,30 @@ Polymer({
      * setup.
      * @type {boolean}
      */
-    isDemoModeSetup: false,
+    isDemoModeSetup: {
+      type: Boolean,
+      value: false,
+    },
 
     /**
      * Whether offline demo mode is enabled. If it is enabled offline setup
      * option will be shown in UI.
      * @type {boolean}
      */
-    offlineDemoModeEnabled: false,
+    offlineDemoModeEnabled: {
+      type: Boolean,
+      value: false,
+    },
 
     /**
      * Whether device is connected to the network.
      * @type {boolean}
      * @private
      */
-    isConnected_: false,
+    isConnected_: {
+      type: Boolean,
+      value: false,
+    },
   },
 
   /** Called when dialog is shown. */