1. @DomName('WorkerPerformance.mark')
  2. @DocsEditable()
  3. @Experimental()
void mark(String markName)

Source 

@DomName('WorkerPerformance.mark')
@DocsEditable()
@Experimental() // untriaged
void mark(String markName) =>
    _blink.BlinkWorkerPerformance.instance.mark_Callback_1_(this, markName);