== Proposed API ==
interface nsIDOMNavigatorXHRBatch : EventTarget {
readonly attribute long maxBatches;
readonly attribute long numBatches;
readonly attribute long numAllBatches;
Promise<IXHRBatch[]> getBatches(); // return submitted batches of the same origin.
Promise<IXHRBatch[]> getAllBatches(); // return all submitted batches, not strict by the same origin if with the permission