Have _embedding_bag_dense_backward match JIT signature. (#19428)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19428
ghimport-source-id: 037efa3df95efc1fbff631826351d1698a3c49ec
Differential Revision: D15003379
Pulled By: gchanan
fbshipit-source-id: f8e82800171f632e28535e416283d858156068ec
