Is parent element from which draggable element was removed somewhere stored?
I have tried to make work arounds on dragStart with either
dataTransfer.setData
or
dataTransfer.addElement
With setData the element gets converted to string addElement exists only in firefox
For easier editing I'm adding jsFiddle
I ended up saving in dragstart event
var parentElement = e.target.parentElement;
e.dataTransfer.setData('ParentId', parentElement.id);
and then getting that parent in drop event by
var parentItem = document.getElementById(e.dataTransfer.getData('ParentId'));