debugFillProperties method
Implementation
@override
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
super.debugFillProperties(properties);
properties
..add(DiagnosticsProperty<Key>('key', key))
..add(DiagnosticsProperty<Rect>('widgetRect', _computeWidgetBounds()))
..add(DiagnosticsProperty<Rect>('clipRect', _computeClipRect()));
}