_transform(point) {
    const matrix = this._matrix;
    const { x, y } = point;
    point.x = matrix[0] * x + matrix[1] * y + matrix[4];
    point.y = matrix[2] * x + matrix[3] * y + matrix[5];
    return point;
  }
Destructive

[ x ] = [ a  b  tx ] [ x ] = [ a * x + b * y + tx ]
[ y ] = [ c  d  ty ] [ y ] = [ c * x + d * y + ty ]

@param  {L.Point} point
@return {L.Point}