Make OSS libhermes ABI compatible with RN

Summary:
We removed a method that RN currently uses, which means that Hermes 0.2.x can not be used with RN <=0.60.5. See facebook#109

This diff adds a dummy passthrough method for linking compatibility.

Reviewed By: mhorowitz

Differential Revision: D17351288

fbshipit-source-id: 7d98af7065064dd47f66dba9ca82ac1192dff133

Clean up unused createStoreOwnPropertyInst

Summary:
We have 4 diferent versions of createStoreOwnPropertyInst, defined in different places in IRBuilder.h.
Only 2 are used and one of them only has one occurance. Those definitions seem unnecessary to me and only increase the complexity of the API.
Clean them up

Reviewed By: dulinriley

Differential Revision: D16496423

fbshipit-source-id: 0eba772aac774921d4fcd4463cdfa5f96db4ea83

Initial commit

fbshipit-source-id: 75e378602933ab4aa91677dfa509a67063e64516