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