src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts/NotebookCellList/isElementAboveViewport
class NotebookCellList:	isElementAboveViewport(index: number) {
		const elementTop = this.view.elementTop(index);
		const elementBottom = elementTop + this.view.elementHeight(index);

		return elementBottom < this.scrollTop;
	}