[FIX] barcodes: barcode input

If the barcode input is hidden, it isn't possible to focus it and thus
it isn't possible to actually use it.

related to rev b4a8338959

addons/barcodes/static/src/js/barcode_events.js

@@ -65,7 +65,6 @@ var BarcodeEvents = core.Class.extend(mixins.PropertiesMixin, {
                     'top': '50%',
                     'transform': 'translateY(-50%)',
                     'z-index': '-1',
-                    'visibility': 'hidden',
                 },
             });
             // Avoid to show autocomplete for a non appearing input