eb11762 Fix UI_driver.has_class exception. Handle situation when element has no class attribute

Authored and Committed by stsymbal 5 years ago
    Fix UI_driver.has_class exception. Handle situation when element has no class attribute
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>