refresh method
void
refresh()
Implementation
void refresh() {
// Keep numeric properties (0..length-1) in sync so JS indexed access works:
// `sheet.cssRules[0]` → getProperty('0').
final props = dynamicProperties;
props.removeWhere((key, _) => int.tryParse(key) != null);
for (int i = 0; i < length; i++) {
final int index = i;
props['$index'] = BindingObjectProperty(getter: () => item(index));
}
}