Use `ALoc.source` rather than converting to `Loc.t`
Use `ALoc.source` rather than converting to `Loc.t`

Reviewed By: samwgoldman

Differential Revision: D10062954

fbshipit-source-id: 04f1c16e4ba0a05d173ec7a954aa702dea294687

jamesgpearce/flow,mroch/flow,samwgoldman/flow,gabelevi/flow,popham/flow,facebook/flow,samwgoldman/flow,popham/flow,jamesgpearce/flow,jamesgpearce/flow,facebook/flow,AgentME/flow,facebook/flow,jamesgpearce/flow,AgentME/flow,samwgoldman/flow,popham/flow,gabelevi/flow,popham/flow,mroch/flow,AgentME/flow,jamesgpearce/flow,facebook/flow,samwgoldman/flow,AgentME/flow,samwgoldman/flow,mroch/flow,mroch/flow,samwgoldman/flow,facebook/flow,gabelevi/flow,mroch/flow,gabelevi/flow,AgentME/flow,popham/flow,popham/flow,gabelevi/flow,gabelevi/flow,mroch/flow,gabelevi/flow,facebook/flow,mroch/flow,popham/flow,jamesgpearce/flow,facebook/flow,samwgoldman/flow,jamesgpearce/flow