Remove $PropertyType shim

Summary: Changelog: [Internal]

Reviewed By: gkz

Differential Revision: D72347503

fbshipit-source-id: 11d00394a0b0e50a28aefdbb984a55ebdbc5bb58

Author: SamChou19815

packages/react-native/flow/global.js

@@ -86,5 +86,3 @@ declare var global: {
   // Undeclared properties are implicitly `any`.
   [string | symbol]: any,
 };
-
-type $PropertyType<T, K> = T[K];