[BUG] modal appears and overlaps screen if parentElement is gone

[woutersteven]

Describe the bug
Perhaps not really a bug, but would suggest a console log for troubleshooting.

If you have an Ionic Tabs app, and append the pane to a custom element inside the tabs at the bottom, for example

<div class="cupertino-append" style="z-index: 1000 !important;"></div>

Then navigating to another component (that's not part of the tabs) and then navigating back using the back button of your browser, will show the modal open and unable to be dismissed, because the parentElement is gone. But the modal remains overlapping the rest of the page.

I realize this is an edge case and doesn't affect people that append to body or ion-content. In my case I also attached it to an element that won't disappear, regardless of the tab routing. But it would be helpful if it could somehow be caught in the console... not sure if thats possible.

[roman-rr]

Related to #233, you might pass it to some global vars, singleton, or window object.
But good to make panes accessible from window object from pane core as well.