code: function scale(out, a, v) {
    var x = v[0],
        y = v[1];
  
    out[0] = x * a[0];
    out[1] = x * a[1];
    out[2] = x * a[2];
  
    out[3] = y * a[3];
    out[4] = y * a[4];
    out[5] = y * a[5];
  
    out[6] = a[6];
    out[7] = a[7];
    out[8] = a[8];
    return out;
  }
docs: Scales the mat3 by the dimensions in the given vec2
  
  @param {mat3} out the receiving matrix
  @param {mat3} a the matrix to rotate
  @param {vec2} v the vec2 to scale the matrix by
  @returns {mat3} out