The goal of this page is to show two animation strategies, and monitor
the smoothness of each. One is a continuously looping CSS
animation of the transform property. The other is a requestAnimationFrame
loop which updates the transform property.
The jank checkbox introduces random jank via javascript. On browsers that
execute CSS animations on another thread, the jank will affect the
responsiveness of javascript but the CSS animation should appear visually
smooth. The requestAnimationFrame animation will start to lag behing. A
good FPS monitoring API should be able to show this happening.