After data update the DataGrid selectedItem doesn't match selectedIndex.

@see http://forums.adobe.com/message/2916571

Steps to reproduce:

1. Create a DataGrid with bindable dataSource and a Sort Function, and apply the sort.
2. Select the row at index 0 by clicking on row 0.
3. (Without changing the selection) update row at index 1, so that the sort will move row 1 to row 0. Suggest a separate button that does this.
4. Row 1 moves to row 0, row 0 moves to row 1 - selection moves to row 1 (stays on corect object), this is expected since the row object moved down one row.
5. Click on row 0 but nothing happens, the change event doesn't fire. Even though row 1 is selected and you click on row 0 nothing happens.

Actual Results:
change event doesn't fire becuase the selectedItem and selectedIndex property don't match.

Expected Results:
The row change event should fire.

Workaround (if any):
After updating the data call refresh or manually set the selectedItem or selectedItems.