src/vs/platform/theme/common/themeService.ts/isThemeIcon
	export function isThemeIcon(obj: any): obj is ThemeIcon {
		return obj && typeof obj === 'object' && typeof (<ThemeIcon>obj).id === 'string' && (typeof (<ThemeIcon>obj).color === 'undefined' || ThemeColor.isThemeColor((<ThemeIcon>obj).color));
	}