Summary:
Cleans up `InitializeJavaScriptAppEngine` in a few ways:
- Fix bug where `global.navigation.geolocation` was being assigned to `global`.
- Rename `polyfillGlobal` to `defineProperty`.
- Rename `polyfillLazyGlobal` to `defineLazyProperty`.
- Inline `polyfillIfNeeded` (only used once).
- Rename `setUpMapAndSet` to `setUpCollections`.
- Add `flow`.
I've changed `defineProperty` and `defineLazyProperty` to always accept an `object` property since it is not only used for defining properties on `global`.
Reviewed By: davidaurelio
Differential Revision: D3472147
fbshipit-source-id: 492da62a303cf040211c386fa6260789e50b43c1
eadbb919c3