[MD settings] remove unused categorySelected property

chrome/browser/resources/settings/site_settings_page/site_settings_page.js

Index: chrome/browser/resources/settings/site_settings_page/site_settings_page.js
diff --git a/chrome/browser/resources/settings/site_settings_page/site_settings_page.js b/chrome/browser/resources/settings/site_settings_page/site_settings_page.js
index 19e572795c7efc9ac46a91cb95058b89b2aa663f..c2f031d54c38e1ea43d9acc06292e3d678c601ae 100644
--- a/chrome/browser/resources/settings/site_settings_page/site_settings_page.js
+++ b/chrome/browser/resources/settings/site_settings_page/site_settings_page.js
@@ -20,14 +20,6 @@ Polymer({
         return loadTimeData.getBoolean('enableSiteSettings');
       },
     },
-
-    /**
-     * The category selected by the user.
-     */
-    categorySelected: {
-      type: String,
-      notify: true,
-    },
   },
 
   ready: function() {