src/vs/editor/common/config/editorOptions.ts/_scrollbarVisibilityFromString
function _scrollbarVisibilityFromString(visibility: string | undefined, defaultValue: ScrollbarVisibility): ScrollbarVisibility {
	if (typeof visibility !== 'string') {
		return defaultValue;
	}
	switch (visibility) {
		case 'hidden': return ScrollbarVisibility.Hidden;
		case 'visible': return ScrollbarVisibility.Visible;
		default: return ScrollbarVisibility.Auto;
	}
}