PerformanceEntry
Encapsulates a single performance metric that is part of the performance
timeline. A performance entry can be directly created by making a performance
mark or measure (for example by calling the .mark() method) at an explicit
point in an application.
class PerformanceEntry { }
readonly duration: number;
readonly entryType: string;
readonly name: string;
readonly startTime: number;
toJSON(): any;