Revert "Check for innerXXX before clientXXX"
Revert "Check for innerXXX before clientXXX"

document.documentElement.clientHeight seems the most reliable solution
because it removes the scrollbars from the viewport as expected,
window.innerHeight do not.

This reverts commit ea3d771070a6c3f4882637d848094515c9bea346.

fasterize/in-viewport,fasterize/in-viewport,ipy/in-viewport,tzi/in-viewport,vvo/in-viewport,vvo/in-viewport,ipy/in-viewport,tzi/in-viewport