[FIX] website: prevent page overflow with mobile menu open

Since [commit 1] replaced the mobile menu, a bug appeared on Safari
where the `#wrapwrap` element would still be scrollable even with the
menu open and even though the `body` has `overflow: hidden;`.
This commit fixes it.

[commit 1]: https://github.com/odoo/odoo/commit/bc13176de8d66bbdc1c536017b1f046c5fd31a86

task-3584299

closes odoo/odoo#141154

Signed-off-by: Romain Derie (rde) <rde@odoo.com>

addons/website/static/src/js/content/menu.js

@@ -661,6 +661,8 @@ publicWidget.registry.HeaderGeneral = publicWidget.Widget.extend({
         'hidden.bs.collapse #top_menu_collapse': '_onCollapseHidden',
         "show.bs.modal #o_search_modal": "_onSearchModalShow",
         "shown.bs.modal #o_search_modal": "_onSearchModalShown",
+        "shown.bs.offcanvas #top_menu_collapse_mobile": "_onMobileMenuToggled",
+        "hidden.bs.offcanvas #top_menu_collapse_mobile": "_onMobileMenuToggled",
     },
 
     //--------------------------------------------------------------------------
@@ -679,6 +681,14 @@ publicWidget.registry.HeaderGeneral = publicWidget.Widget.extend({
     _onCollapseHidden() {
         this.el.classList.remove('o_top_menu_collapse_shown');
     },
+    /**
+     * @private
+     */
+    _onMobileMenuToggled(ev) {
+        // TODO: Fix for Safari. Once the scroll is moved back from the
+        //       #wrapwrap to the body, this code should not be needed anymore.
+        document.querySelector("#wrapwrap").classList.toggle("overflow-hidden");
+    },
     /**
      * @private
      */