addAction method
Implementation
void addAction(Action action, Node target, bool paused) {
var element = _hashTargetList[target];
if (element == null) {
element = ActionHashElement();
element.target = target;
element.paused = paused;
_hashTargetList[target] = element;
}
element.actionList.add(action);
action.startWithTarget(target);
}