// https://w3c.github.io/user-timing/#dom-performancemark
[Exposed=(Window,Worker)]
interface PerformanceMark : PerformanceEntry {
    constructor(DOMString markName, optional PerformanceMarkOptions markOptions = {});
    readonly attribute any detail;
};

// https://w3c.github.io/user-timing/#ref-for-dom-performancemarkoptions-1
dictionary PerformanceMarkOptions {
    any detail;
    DOMHighResTimeStamp startTime;
};
