Revert "fix bug #3783, instanciate class before calling static method"

This reverts commit 27148aa738defffc4ccfb2971ab6c9cba0c269d1.

-> fix does not work : methods of a class can't be called usçg a variable before PHP 5.3
Temporary workaround for bug #3783 :
       Calling a method from a variable class is not possible before PHP 5.3.