Summary:
Somehow referring to the parent directory doesn't work on Windows. Please don't ask me why. Given that we run a script from outside the package doing it on the top-level seems more consistent anyway.
Pull Request resolved: https://github.com/facebook/flipper/pull/2101
Test Plan: Yarn on Windows succeeds: https://github.com/facebook/flipper/pull/2101/checks?check_run_id=2195613718
Reviewed By: fabiomassimo
Differential Revision: D27335250
Pulled By: passy
fbshipit-source-id: aaccdb3f7e78ca264b371a7723c9bad065919d45
a0a28c2e21