src/vs/platform/undoRedo/common/undoRedoService.ts/ResourceEditStack/getElements
class ResourceEditStack:	public getElements(): IPastFutureElements {
		const past: IUndoRedoElement[] = [];
		const future: IUndoRedoElement[] = [];

		for (const element of this._past) {
			past.push(element.actual);
		}
		for (const element of this._future) {
			future.push(element.actual);
		}

		return { past, future };
	}