Fixed a bug where the last notification could be invisible / faded

if the last notification was small, it was already fading out in
the resting state.

Test: add a small notification without text and title and have it as
      last notification in the shade. Observe that it's not faded out.
Bug: 32437839
Change-Id: I4acd429e363185276fe1f472ecbeddae8f56e45a