Description:
------------
At the moment, calling ReflectionClass::newInstanceWithoutConstructor() on an internal class results in the error:

Class $name is an internal class that cannot be
instantiated without invoking its constructor

For example:

<?php

$reflect = new ReflectionClass('exception');
$myException = $reflect->newInstanceWithoutConstructor();
?>

Will create the error:

Class Exception is an internal class that cannot be instantiated without invoking its constructor.


That's fine (although a bizarre restriction!) because I can work around it using ReflectionClass()::isInternal():

<?
$reflect = new ReflectionClass('Exception');
if ($reflect->isInternal()) { 
    $reflect->newInstanceWithoutConstructor();
}
?>

However, if a class extends an internal class, there's no way to easily detect whether newInstanceWithoutConstructor() will be allowed or not.

<?php
class MyException extends Exception {
	
}


$reflect = new ReflectionClass('MyException');
if ($reflect->isInternal()) {

    $reflect->newInstanceWithoutConstructor();
}

?>

This breaks with the same arbitrary restriction  Class Exception is an internal class that cannot be instantiated without invoking its constructor.



The only way to currently fix this is to loop back through every parent using 

<?php

class MyException extends Exception {
	
}


$reflect = new ReflectionClass('MyException');
$parent = clone $reflect;
while ($parent->getParentClass()) {
    $parent = $parent->getParentClass();
}

if ($parent->isInternal() {
    $reflect->newInstanceWithoutConstructor();

}

?>



This is needlessly verbose.

In an ideal world, I'd like to see the arbitrary restriction applied to internal classes removed entirely and allow them to be created without a constructor.


However, I'm guessing there's a technical reason for that not being feasible so instead, I'd suggest adding a ReflectionClass::getRootClass() method, which
retrieved the top level parent and you could do:

<?php
$reflect = new ReflectionClass('MyException');
if ($reflect->getRootClass()->isInternal()) {
	$reflect->newInstanceWithoutConstructor();
}
?>

For top level classes, getRootClass should return itself (the root class of Exception should return new ReflectionClass('Exception') )