PASS @@toStringTag exists on the prototype with the appropriate descriptor
PASS @@toStringTag must not exist on the instance
PASS Object.prototype.toString applied to the prototype
PASS Object.prototype.toString applied to an instance
PASS Object.prototype.toString applied after modifying the prototype's @@toStringTag
PASS Object.prototype.toString applied to the instance after modifying the instance's @@toStringTag
PASS Object.prototype.toString applied to a null-prototype instance
PASS Object.prototype.toString applied after deleting @@toStringTag