Options: Remove the hidden class, since we override the hidden attribute to set

chrome/browser/resources/options/browser_options.js

Index: chrome/browser/resources/options/browser_options.js
diff --git a/chrome/browser/resources/options/browser_options.js b/chrome/browser/resources/options/browser_options.js
index 8db195c8f64950029b48d06354bbdd5acb5d2f11..871e5206cf07576bd31e58d313a3a2c3169884f8 100644
--- a/chrome/browser/resources/options/browser_options.js
+++ b/chrome/browser/resources/options/browser_options.js
@@ -128,7 +128,7 @@ cr.define('options', function() {
       // Check if we are in the guest mode.
       if (cr.commandLine.options['--bwsi']) {
         // Hide the startup section.
-        $('startupSection').classList.add('hidden');
+        $('startupSection').hidden = true;
       } else {
         // Initialize control enabled states.
         Preferences.getInstance().addEventListener('session.restore_on_startup',