src/vs/workbench/api/common/extHostTreeViews.ts/ExtHostTreeView/getDarkIconPath
class ExtHostTreeView:	private getDarkIconPath(extensionTreeItem: vscode.TreeItem): URI | undefined {
		if (extensionTreeItem.iconPath && !(extensionTreeItem.iconPath instanceof ThemeIcon) && (<{ light: string | URI; dark: string | URI }>extensionTreeItem.iconPath).dark) {
			return this.getIconPath((<{ light: string | URI; dark: string | URI }>extensionTreeItem.iconPath).dark);
		}
		return undefined;
	}