mysql-test/suite/heap/heap.result:
  Added test case
mysql-test/suite/heap/heap.test:
  Added test case
storage/heap/hp_delete.c:
  Fixed that we don't change order of keys for the current key when we delete them from the hash table.
  Fixed that 'current_hash_ptr' is correct after heap_delete_key().
  Don't "reset current_hash_ptr" on delete; This will improve time a lot for delete of rows when not all rows matches the search criteria.