[TIMOB-16159] MobileWeb: NavigationGroup buttons click event not working

<Alloy>
	<Window>
		<NavigationGroup id="nav">
			<Window id="webWin">
				<RightNavButton>
					<Button class="aboutBtn" onClick="openAbout" />
				</RightNavButton>
				<TableView id="list" />
			</Window>
		</NavigationGroup>
	</Window>
</Alloy>

var openAbout = function() {
	alert('working');
};
$.index.open();

<Alloy>
	<Window>
		<NavigationGroup id="nav">
			<Window id="webWin">
				<TableView id="list" />
			</Window>
		</NavigationGroup>
	</Window>
</Alloy>

var btn = Ti.UI.createButton({
	title : 'aaa'
});
btn.addEventListener('click', function() {
	alert('working');
});
$.webWin.rightNavButton = btn;