dispose method
Called when the scroll view stops performing this activity.
Implementation
@mustCallSuper
void dispose() {
// TODO(polina-c): stop duplicating code across disposables
// https://github.com/flutter/flutter/issues/137435
if (kFlutterMemoryAllocationsEnabled) {
FlutterMemoryAllocations.instance.dispatchObjectDisposed(object: this);
}
_isDisposed = true;
}