Consider using the browser's scroll-behavior for smooth scrolling

[philc]

It seems like all modern browsers now support smooth scrolling as an argument to window.scrollBy. Can we rely on the browser's smooth scrolling implementation and remove the Vimium "use smooth scrolling" and "step size" options?

It seems reasonable to me that if the user has disabled smooth scrolling in the browser, then Vimium will inherit that preference and not have smooth scrolling. What do you think?

The first step is to POC this and see if the browser's implementation is equivalent to Vimium's current implementation.

Related issues:

• #3701
• #3641
• #2650
• #4273
• #3606

[gdh1995]

The smooth scrolling is not as convenient as I once expected: if I hold on j to scroll longer, then a sequence of element.scrollBy({ y: 60, behavior: "smooth"}) will behave very weird, mainly because browser always interrupts an old scrolling and starts a new one.