Summary:
A domain should not definite its initial state, since distinct users of the domain may want to choose different initial values.
For example, one user might want to bind all of the formals to some special values, and one user might want the initial domain to be an empty map
This diff makes this distinction clear in the types by (a) requiring the initial state to be passed to the abstract interpreter and (b) lifting the requirement that abstract domains define `initial`.
Reviewed By: jberdine
Differential Revision: D4359629
fbshipit-source-id: cbcee28
Sam Blackshear