src/vs/workbench/browser/parts/views/treeView.ts/TreeRenderer/isFileKindThemeIcon
class TreeRenderer:	private isFileKindThemeIcon(icon: ThemeIcon | undefined): boolean {
		if (icon) {
			return icon.id === FileThemeIcon.id || icon.id === FolderThemeIcon.id;
		} else {
			return false;
		}
	}