Mutate newDirtyPaths instead of creating a new array every iteration (#2559)
Mutate newDirtyPaths instead of creating a new array every iteration (#2559)

* Mutate newDirtyPaths instead of creating a new array every iteration

* Switch to map + Array.prototype.concat.apply to improve readability

* Update editor.js

isubastiCadmus/slate,ianstormtaylor/slate,ianstormtaylor/slate