Add marks and measures to performance timeline

PerfMeasure.ts

const START = `start`;
const END = `end`;

export class PerfMeasure {
  public measureName: string;
  public started: boolean;
  public ended: boolean;

  constructor(measureName: string) {
    this.measureName = measureName;
    this.started = false;
    this.ended = false;
  }

  start() {
    if (!this.started) {
      this._perfMark(START);
      this.started = true;
    }
    return this;
  }

  end() {
    if (this.started && !this.ended) {
      this._perfMark(END);
      this._perfMeasure();
      this.ended = true;
    }
    return this;
  }

  _perfMark(markType) {
    if (typeof performance !== `undefined` && performance.mark) {
      performance.mark(`${this.measureName}:${markType}`);
    }
  }

  _perfMeasure() {
    if (typeof performance !== `undefined` && performance.measure) {
      performance.measure(this.measureName, `${this.measureName}:${START}`, `${this.measureName}:${END}`);
    }
  }
}