The goal of this page is to monitor smoothness of a continuously looping
CSS animation of 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 animation should appear visually
smooth. A good FPS monitoring API should be able to show this happening.
When animate is unchecked, the page goes idle. A good FPS monitoring API
should have zero CPU consumption. requestAnimationFrame polling loops,
unfortunately, will still spin the CPU. :(