Go to System Preferences -> Mission Control.
Look at the bottom half of the Mission Control window
Just to the right of the words "Mission Control:", click on the dropdown menu that's on the left, and choose F9.
Just below that, you'll see the prompt "Application windows:". Just to the right of those words, click on the dropdown menu that's on the left, and choose F10.
That will set F9 and F10 as they were in Snow Leopard.