Guarded against ArrayOutOfBounds

In some monkey tests, getAdapterPosition returns -1 (for example, if the
ViewHolder is not bound). In this case, we shouldn't proceed with the
moving operation.

Test: manual
Change-Id: I1eccc2c60136ddf5cc0175d88a3fddbe1d2a5a97
Fixes: 117769352
Fixes: 116871219