Simplification initialization vector

    /**
     * Normalize this Vector.  向量归一化
     *
     * Makes the vector a unit length vector (magnitude of 1) in the same direction.
     *
     * @method Phaser.Math.Vector2#normalize
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    normalize: function ()
    {
        var x = this.x;
        var y = this.y;
        var len = x * x + y * y;

        if (len > 0)
        {
            len = 1 / Math.sqrt(len);

            this.x = x * len;
            this.y = y * len;
        }

        return this;
    },

    /**
     * Right-hand normalize (make unit length) this Vector. Right-hand normalize归一化
     *
     * @method Phaser.Math.Vector2#normalizeRightHand
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    normalizeRightHand: function ()
    {
        var x = this.x;

        this.x = this.y * -1;
        this.y = x;

        return this;
    },