PerformanceMark
PerformanceMark is an abstract interface for PerformanceEntry objects with an entryType of "mark". Entries of this type are created by calling performance.mark() to add a named DOMHighResTimeStamp (the mark) to the browser's performance timeline.
var PerformanceMark: {
prototype: PerformanceMark;
new (markName: string, markOptions?: PerformanceMarkOptions): PerformanceMark;
};