remove unused accumulation buffer.
remove unused accumulation buffer.

bhouston/three.js,bhouston/three.js,Jozain/three.js,Jozain/three.js,Jozain/three.js,bhouston/three.js,bhouston/three.js,bhouston/three.js,Jozain/three.js,bhouston/three.js,Jozain/three.js,Jozain/three.js