[bug] valueOf / toString

[NikolayMakhonin]

Remove please brackets after Object.prototype.valueOf() and Object.prototype.toString()

        if (a.valueOf !== Object.prototype.valueOf() && b.valueOf !== Object.prototype.valueOf()) {
            return a.valueOf() === b.valueOf();
        }

        if (a.toString !== Object.prototype.toString() && b.toString !== Object.prototype.toString()) {
            return a.toString() === b.toString();
        }