Remove is_element_empty()

[kalenjohnson]

Move is_element_empty into closure for Nav Walker. Especially since is_element_empty was lying

[QWp6t]

Could this work as an alternative?

$classes = array_map('trim', $classes);
$classes = array_filter($classes);

I'm on my phone and the app I'm using doesn't let me see the code while I'm writing this message, but I might have inverted the logic. If so, array_diff should cover it.