Remove unneeded casts in hack generator
Remove unneeded casts in hack generator

Reviewed By: yfeldblum

Differential Revision: D26760192

fbshipit-source-id: 70547e387085e49cfa401ac7db5f5a1af56dbcbb

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift