message: Fix inaccurate comment.
diff: @@ -28,7 +28,7 @@ import { FloatRgb } from "./FloatRGBA";
  * x: diffuse and specular weights
  * y: texture weight and specular red
  * z: specular green and blue
  - * z: specular exponent
  + * w: specular exponent
  *
  * This packing is motivated by the limited max number of varying vectors guaranteed by WebGL.
  * A varying is used because:
  