src/vs/base/browser/ui/list/listWidget.ts/SelectionTrait/renderIndex
class SelectionTrait:	override renderIndex(index: number, container: HTMLElement): void {
		super.renderIndex(index, container);

		if (this.setAriaSelected) {
			if (this.contains(index)) {
				container.setAttribute('aria-selected', 'true');
			} else {
				container.setAttribute('aria-selected', 'false');
			}
		}
	}