Stopped mutating nodes with a `declare` modifier#1458

Merged

nicojs merged 3 commits intostryker-mutator:masterfrom JoshuaKGoldberg:typescript-not-mutating-declare-nodes

Mar 26, 2019

+77-7

Commits on Mar 21, 2019

Stopped mtuating nodes with a declare modifier
Josh Goldberg
committed
PR feedback
Josh Goldberg
committed

Commits on Mar 23, 2019

Split and clarified new unit test
Josh Goldberg
committed