Replace Var by VariableIndex in Lineage nodes, paves the way for adding fields
Replace Var by VariableIndex in Lineage nodes, paves the way for adding fields

Reviewed By: rgrig

Differential Revision: D41013586

fbshipit-source-id: f522528d583b7b9161cbf7afdcf1dbc1aeac79a5

facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer