DOM benchmark is using Main Thread animations

[bramus]

Because of the way the DOM benchmark is written – by constantly updating the style value in a rAF – these updates are performed on the main thread and are constantly recalculating styles.

Consider running the animations via WAAPI Animations or CSS Animations instead, so that the browser can try and run these on the compositor.

I have done so here and can PR these changes:

• https://bramus.github.io/canvas-engines-comparison/dom-waapi.html
• https://bramus.github.io/canvas-engines-comparison/dom-css.html