I've tested the new Perf tools on one of the screens in one app I'm working on and it works great :)

One thing I wanted also on the old one Perf tools was to be able to check whether the Perf tools are started or stopped, so basically exposing `ReactDebugTool`'s `isProfiling` variable. My use for that is that I have a keyboard shortcut (in development) bound to start/stop the Perf tools and currently I'm forced to maintain such a variable myself to know whether to start or stop (which gets out of sync if I start/stop the perf tools without the keyboard shortcut).

If you don't think it's worthwhile to expose `isProfiling` feel free to close this issue.

if (!stats.counts[timerType]) {
      stats.counts[timerType] = 0;
    }
    affectedIDs[key][instanceID] = true;
    applyUpdate(stats);
  }
  flushHistory.forEach(flush => {
    var {measurements, treeSnapshot} = flush;
    measurements.forEach(measurement => {
      var {duration, instanceID, timerType} = measurement;
      updateAggregatedStats(treeSnapshot, instanceID, timerType, stats => {
        stats.totalDuration += duration;
        stats.durations[timerType] += duration;
        stats.counts[timerType]++;
      });
    });
  });
  return Object.keys(aggregatedStats)
    .map(key => ({
      ...aggregatedStats[key],
      instanceCount: Object.keys(affectedIDs[key]).length,
    }))
    .sort((a, b) =>
      b.totalDuration - a.totalDuration
    );
}
function getInclusive(flushHistory = getFlushHistory()) {
  var aggregatedStats = {};
  var affectedIDs = {};
  function updateAggregatedStats(treeSnapshot, instanceID, applyUpdate) {