don't scroll search list into view in old FF

couldn't find the reason in a couple minutes I can waste on this

popup/search-results.js

@@ -134,9 +134,11 @@ window.addEventListener('showStyles:done', function _() {
 
       if (scrollToFirstResult && list.children[0]) {
         scrollToFirstResult = false;
+        if (!FIREFOX || FIREFOX >= 55) {
           list.children[0].scrollIntoView({behavior: 'smooth', block: 'start'});
         }
       }
+    }
 
     /**
      * @returns {Boolean} If we should process more results.