src/vs/base/browser/ui/tree/indexTreeModel.ts/IndexTreeModel/_updateAncestorsRenderNodeCount
class IndexTreeModel:	private _updateAncestorsRenderNodeCount(node: IIndexTreeNode<T, TFilterData> | undefined, diff: number): void {
		if (diff === 0) {
			return;
		}

		while (node) {
			node.renderNodeCount += diff;
			this._onDidChangeRenderNodeCount.fire(node);
			node = node.parent;
		}
	}