List: hangs when detached then reattached to document

[wkeese]

In deliteful/samples/list/PageableList-ObservableArray.html, run this in the console:

var list = document.querySelector("d-pageable-list");
list.parentNode.removeChild(list);
list.placeAt(document.body);

The loading icon will spin endlessly, and the buttons to page the list stop working.

The root issue is that List#attachedCallback() and also delite/StoreMap#attachedCallback() were not designed to be called repeatedly.

List#attachedCallback() assumes that a new query will be starting. It sets busy to true and expects it to be set to false when _initItems() is called:

attachedCallback: dcl.superCall(function (sup) {
    ...
    this._setBusy(true, true);
    ...
}),
...
initItems: function (items) {
    ...
    this._setBusy(false, true);
    ...
},

But actually, a new query doesn't start, see ibm-js/delite#435.