Bug 1889157 - Dont use Promise.withResolvers in browser_LegacyHeartbeat.js r=chumphreys a=RyanVM

    sandbox.stub(client, "get").resolves([]);

    // Override Heartbeat so we can get the instance and manipulate it directly.

    const heartbeatDeferred = Promise.withResolvers();

    let resolveHeartbeatPromise;

    const heartbeatPromise = new Promise(resolve => {

      resolveHeartbeatPromise = resolve;

    });

    class TestHeartbeat extends Heartbeat {

      constructor(...args) {

        super(...args);

        heartbeatDeferred.resolve(this);

        resolveHeartbeatPromise(this);

      }

    }

    ShowHeartbeatAction.overrideHeartbeatForTests(TestHeartbeat);

    try {

      await RecipeRunner.run();

      const heartbeat = await heartbeatDeferred.promise;

      const heartbeat = await heartbeatPromise;

      // We are going to simulate the timer timing out, so we do not want it to

      // *actually* time out.

      heartbeat.endTimerIfPresent("surveyEndTimer");