src/vs/base/common/scrollable.ts/SmoothScrollingOperation/_tick
class SmoothScrollingOperation:	protected _tick(now: number): SmoothScrollingUpdate {
		const completion = (now - this.startTime) / this.duration;

		if (completion < 1) {
			const newScrollLeft = this.scrollLeft(completion);
			const newScrollTop = this.scrollTop(completion);
			return new SmoothScrollingUpdate(newScrollLeft, newScrollTop, false);
		}

		return new SmoothScrollingUpdate(this.to.scrollLeft, this.to.scrollTop, true);
	}