The current_theme_supports should have default args test

[pbearne]

You can pass a second arg to the current_theme_supports() function but if this is not in the switch if is not handled

I believe we should make the simple in_array test the default test to that the current_theme_supports function can be used with extra args without have to change core code

Trac ticket: https://core.trac.wordpress.org/ticket/56488