Description:
------------
In PHP 7.3 the instanceof operator was changed to allow literals to appear as the first argument.

However, this is not reflected on the Type Operators page at https://www.php.net/manual/en/language.operators.type.php where it states that, "Constants, however, are not allowed." 

It then gives an example:

var_dump(FALSE instanceof stdClass);

The expected output for that is given as:

PHP Fatal error:  instanceof expects an object instance, constant given

However, that is no longer true for PHP 7.3+ where the result will be bool(false).