_growNode(width, height) {
    const canGrowBottom = width <= this.root.width;
    const canGrowRight = height <= this.root.height;
    const shouldGrowRight = canGrowRight && (this.root.height >= (this.root.width + width));
    const shouldGrowBottom = canGrowBottom && (this.root.width >= (this.root.height + height));

    if (shouldGrowRight) {
      return this._growRight(width, height);
    }

    if (shouldGrowBottom) {
      return this._growBottom(width, height);
    }

    if (canGrowRight) {
      return this._growRight(width, height);
    }

    if (canGrowBottom) {
      return this._growBottom(width, height);
    }

    return null;
  }
Grow the sprite

@param {number} width        Width
@param {number} height       Height
@returns {object|null}       Node