Map not disposed when containing page is closed

[cpetrov]

Example:

let navigation = new tabris.NavigationView({left: 0, top: 0, right: 0, bottom: 0}).appendTo(tabris.ui.contentView);

new tabris.Page({title: 'Page 1'}).appendTo(navigation);

setTimeout(() => {
  let page = new tabris.Page({title: 'Map'}).appendTo(navigation);

  new esmaps.Map({
    left: 0, right: 0, top: 0, bottom: 0
  }).appendTo(page);
}, 400);

When the map page is closed, ESMap.destroy does not get called.

However, ESMap.destroy gets called when the map gets disposed explicitly, i.e. when map.dispose() is called in JavaScript.