look-at: setting coordinates is not working anymore (a-frame v0.9.0)

look-at="#my-target" works whereas look-at="0 0 0" does not. I investigated and saw that `self.data` is empty in `function update`: 

https://github.com/supermedium/superframe/blob/master/components/look-at/index.js#L50 

I tried to fix it but could not. It worked with a-frame v0.8.2