Filter referrers before visiting (#82)
Filter referrers before visiting (#82)

* handle cross-block propagation

* fix broken test (typo)

* address review comments

* split long line on &&

* use dedicated stack

* get rid of extraneous whitespace diff

* rebase + fix conflict

* remove duplicate code

* document referrersToVisit
google/go-flow-levee,google/go-flow-levee