main
add `allowTopLevelThis` option to `transform-modules-systemjs` (#10780)
Enable `external-helpers` by default in tests (#12911)
fix(systemjs): support __proto__ as an export name (#18032)
Move all runtime helpers to individual files (#16495)
Rename `-proposal-`s that became standard to `-transform-` (#15614)
archive stage 4 parser plugins (#13717)