[FIX] website: fix main menu navbar disappearing

Before this commit, the "purple" main menu navbar disappeared before
the editor was loaded (after clicking on the "Edit" button).

task-2652381

closes odoo/odoo#76920

X-original-commit: 63aebbfb0749c59bd336e3431aed12a902d3bf13
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/static/src/js/editor/snippets.editor.js

@@ -35,8 +35,8 @@ weSnippetEditor.SnippetsMenu.include({
     /**
      * @override
      */
-    start() {
-        this._super(...arguments);
+    async start() {
+        await this._super(...arguments);
         this.$currentAnimatedText = $();
 
         this.__onSelectionChange = ev => {