Hard-disable the use of sponsored tiles.

toolkit/modules/NewTabUtils.jsm

@@ -249,10 +249,15 @@ var AllPages = {
    * Returns whether the history tiles are enhanced.
    */
   get enhanced() {
+#ifdef MC_BASILISK
+    // Hard-block the use of sponsored tiles.
+    return false;
+#else
     if (this._enhanced === null)
       this._enhanced = Services.prefs.getBoolPref(PREF_NEWTAB_ENHANCED);
 
     return this._enhanced;
+#endif
   },
 
   /**

toolkit/modules/moz.build

@@ -57,7 +57,6 @@ EXTRA_JS_MODULES += [
     'Locale.jsm',
     'Log.jsm',
     'Memory.jsm',
-    'NewTabUtils.jsm',
     'NLP.jsm',
     'ObjectUtils.jsm',
     'PageMenu.jsm',
@@ -104,6 +103,8 @@ EXTRA_JS_MODULES += [
 EXTRA_JS_MODULES.third_party.jsesc += ['third_party/jsesc/jsesc.js']
 EXTRA_JS_MODULES.sessionstore += ['sessionstore/Utils.jsm']
 
+EXTRA_PP_JS_MODULES += ['NewTabUtils.jsm']
+
 if not CONFIG['MOZ_WEBEXTENSIONS']:
   EXTRA_PP_JS_MODULES += ['UpdateChannel.jsm']