unTrack method
Implementation
void unTrack(HtmlElement element) {
// Cancel subscriptions to events for removed element.
var subs = _subscriptionsForElement(element);
for (StreamSubscription s in subs) {
s.cancel();
}
_subscriptions.remove(element);
if (_dragSubscriptions[element] != null) {
_dragSubscriptions[element]?.cancel();
}
_dragSubscriptions.remove(element);
}