Revert "XJS -> JSX"
Revert "XJS -> JSX"

This temporarily reverts commit d7fdf03ae35ea9ee6b4519cb99d6fecdde737764
so that I can publish one last v0.6.x version without that commit.

gabelevi/ast-types,benjamn/ast-types,benjamn/ast-types,benjamn/ast-types,jamestalmage/ast-types,cpojer/ast-types,marcioj/ast-types