Description:
------------
The original class is checked, but the checks a too lax on the alias 
itself. 

I suggest the alias's name should follow the same rules as the class 
itself.

Admittedly, the following may work in conjunction with the problem 
reported : 
<?php

class foo { }

var_dump(class_alias('foo', '$$$'));

$b = "$$$";
$a = new $b;
var_dump($a);
?>


Reproduce code:
---------------
<?php

class foo { }

var_dump(class_alias('foo', '999'));
var_dump(class_alias('foo', ''));
var_dump(class_alias('foo', true));
var_dump(class_alias('foo', false));
var_dump(class_alias('foo', null));
var_dump(class_alias('foo', '$$$'));
var_dump(class_alias('foo', ';;'));
var_dump(class_alias('foo', '"'));
var_dump(class_alias('foo', '::'));

?>


Expected result:
----------------
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)


Actual result:
--------------
bool(true)
bool(true)
bool(true)
PHP Warning:  Cannot redeclare class  in /Users/alterway/bin/php-
5.3.0RC4/Zend/tests/- on line 8

Warning: Cannot redeclare class  in /Users/alterway/bin/php-
5.3.0RC4/Zend/tests/- on line 8
bool(false)
PHP Warning:  Cannot redeclare class  in /Users/alterway/bin/php-
5.3.0RC4/Zend/tests/- on line 9

Warning: Cannot redeclare class  in /Users/alterway/bin/php-
5.3.0RC4/Zend/tests/- on line 9
bool(false)
bool(true)
bool(true)
bool(true)
bool(true)