src/vs/platform/theme/browser/iconsStyleSheet.ts/UnthemedProductIconTheme/getIcon
class UnthemedProductIconTheme:	getIcon(contribution: IconContribution) {
		const iconRegistry = getIconRegistry();
		let definition = contribution.defaults;
		while (ThemeIcon.isThemeIcon(definition)) {
			const c = iconRegistry.getIcon(definition.id);
			if (!c) {
				return undefined;
			}
			definition = c.defaults;
		}
		return definition;
	}