dillon1000/react

[babel] Invoke gating module as a call expression

This is incredibly obvious in hindsight, but for exposure logging to work 
correctly we need to *call* the underlying `MobileConfig.getBool` function at 
the callsite – otherwise the bool is evaluated once (and only once) when the 
module is loaded. 

Tested internally and verified that in dogfooding the exposure logging was 
working correctly