Fix c&p error

lib/browser/api/dialog.js

@@ -288,7 +288,7 @@ module.exports = {
     }
 
     let {certificate, message} = options
-    if (certificate == null || typeof options !== 'object') {
+    if (certificate == null || typeof certificate !== 'object') {
       throw new TypeError('certificate must be an object')
     }