A little bird told me that they wanted to open-source it but they were waiting for the Oracle v Google lawsuit to conclude, and that dragged on a long time, so maybe they have up.
The team was folded in to the VR/AR org (I presume to develop an applications API that the universe of app developers would be familiar with), but it floundered and went nowhere.
I heard this from someone who was on the team, I was not allowed to actually join or work with them, because I had worked for Apple previously and they were afraid of the Andy Rubin issue, where iOS's actual source code existed in my brain, so theoretically Apple could sue Facebook.