feat(EventHandler) EventHandler does not assume it will be sitting only at the root of the application.
Merge remote-tracking branch 'fork/feature/event-handler' into feature/event-handler

Conflicts:
	lib/core_dom/event_handler.dart
	lib/core_dom/module.dart
	lib/core_dom/view_factory.dart
Allow use of EventHandler within NgComponent
Revert NgApp changes.
Add event handler for element within ShadowDom.
Add event handler playground