Remove unused export_file state in ContextOptimizer
Remove unused export_file state in ContextOptimizer

Reviewed By: samwgoldman

Differential Revision: D25430331

fbshipit-source-id: 04bb366d51d17b4faaad1eea6dfcffae5d91afc8

facebook/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow