Description:
------------
See the code below.

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

namespace foobar;

class foo { }

//var_dump(namespace::);
// Parse error: syntax error, unexpected ')', expecting T_STRING or T_VARIABLE or '$'

// Ok!

$foo = 'foo';

var_dump(new namespace::$foo);
// Fatal error: Class 'foobar' not found 

// var_dump(new namespace::foo); # Ok!

Expected result:
----------------
var_dump(namespace::);
Parse error: syntax error, unexpected ')', expecting T_STRING

or

Support the variable referencing class name.

Actual result:
--------------
Fatal error: Class 'foobar' not found