[Feature Request] PrecomputedAOMask and AO input for ES2

Hello!

While working on my GearVR game, i noticed that the PrecomputedAOMask node is not working with ES2 rendering. It would be nice, if that is added in a future release.

Also the Ambient Occlusion material input is not doing anything on ES2 / ES2 Preview. This might be a bug ?! It can be easily reproduced by just having a 0 constant plugged in and switching between SM5 and ES2 preview(or testing on device).

Thanks!