src/vs/platform/theme/common/tokenClassificationRegistry.ts/equals
	export function equals(s1: any, s2: any): boolean {
		if (s1 === s2) {
			return true;
		}
		return s1 !== undefined && s2 !== undefined
			&& (s1.foreground instanceof Color ? s1.foreground.equals(s2.foreground) : s2.foreground === undefined)
			&& s1.bold === s2.bold
			&& s1.underline === s2.underline
			&& s1.strikethrough === s2.strikethrough
			&& s1.italic === s2.italic;
	}