Multi Texture Support does not work

[andrinr]

Conserning branch: multi-texture, npm version @beta
FBO: drawbufferextension is not loaded properly:

TypeError: this.drawBufferExtension.drawBuffersWEBGL is not a function

  87 |       ];
  88 | 
> 89 |       this.drawBufferExtension.drawBuffersWEBGL(this.colorAttachments.slice(0,this.props.outputTextures));
     |                                ^
  90 |     }
  91 | 
  92 |