signature builder kind
signature builder kind

Summary:
A signature of a file is defined by its exports, which are closed over by an environment that
carries information about local bindings and import bindings.

This diff introduces types to describe such bindings.

Reviewed By: pakoito

Differential Revision: D9310776

fbshipit-source-id: 5210fc35ad54b810be0738eef7cf58fbdf0d6777

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