CSSRuleList
A CSSRuleList is an (indirect-modify only) array-like object containing an ordered collection of CSSRule objects.
interface CSSRuleList {
[index: number]: CSSRule;
readonly length: number;
[[Symbol.iterator]](): IterableIterator<CSSRule>;
item(index: number): CSSRule | null;
}var CSSRuleList: {
prototype: CSSRuleList;
new (): CSSRuleList;
};