Fix for the CR #6878399 introduced a new method SwingUtilities.getParentViewport()
which looks for the first component's ancestor which is not an inctance of JLayer
and returns JViewport if this ancestor is instance of JViewport,
otherwise returns null.

This has quite a confusing name and it is too specific,
because users may require more similar methods like getParentApplet() etc...

Moreover it turned out that JTable needs another method
which looks for the first JViewport's descendant which is not and instance of JLayer