Trackable event incorrect when beforeId matched item being updated

[edhager]

This issue started with SitePen/dgrid#1365.

The problem is in dstore/Trackable. When a call to a trackable store's put method is updating an item using the beforeId option set to the item's id, the item is removed from Trackable's arrays.
This in turn caused the Trackable event that was generated to not have an index property.

store.put(store.getSync(1), { beforeId: 1 });