Attach event listeners on the host (this) element.
void addHostListeners() {
var events = _element._eventDelegates;
if (events.isEmpty) return;
_eventsLog.fine(() => '[$_name] addHostListeners: $events');
// NOTE: host events look like bindings but really are not;
// (1) we don't want the attribute to be set and (2) we want to support
// multiple event listeners ('host' and 'instance') and Node.bind
// by default supports 1 thing being bound.
events.forEach((type, methodName) {
// Dart note: the getEventHandler method is on our PolymerExpressions.
PolymerGesturesJs.addEventListener(
this, type,
Zone.current.bindUnaryCallback(
element.syntax.getEventHandler(this, this, methodName)));
});
}