[Bug 1055270] [KK Only][Flame][Camera] Face detection coordinates are in...

...verted
See, I think it would be even more confusing if you conditionally passed in pre-swapped `viewportWidth` and `viewportHeight` arguments to this function. I would expect (as the caller of this function) that `viewportWidth` and `viewportHeight` are the *actual* width/height of the viewport that the user sees.