Allow zIndex to useNativeDriver (#27418)

Summary:
STYLES_WHITELIST
+zIndex
Pull Request resolved: #27418

Test Plan: Working on sim and device.

Differential Revision: D19644753

Pulled By: shergin

fbshipit-source-id: 9a3516f65de7011f7e91587e62153e083504d283

Author: mackenziemance

Libraries/Animated/src/NativeAnimatedHelper.js

@@ -172,6 +172,7 @@ const STYLES_WHITELIST = {
   borderTopRightRadius: true,
   borderTopStartRadius: true,
   elevation: true,
+  zIndex: true,
   /* ios styles */
   shadowOpacity: true,
   shadowRadius: true,