Fixed access to element in size tensor for scripting (#32652)
Summary:
when using scripting, there was an error in attempting to access a
specific element from within the size tensor.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32652
Reviewed By: hl475
Differential Revision: D19610726
Pulled By: houseroad
fbshipit-source-id: bca49927bbe71dbe7e7d7edf301908fe79e089b5
