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.

warning(
    warnedAboutPrintDOM,
    '`ReactPerf.printDOM(...)` is deprecated. Use ' +
    '`ReactPerf.printOperations(...)` instead.'
  );
  warnedAboutPrintDOM = true;
  return printOperations(measurements);
}
var warnedAboutGetMeasurementsSummaryMap = false;
function getMeasurementsSummaryMap(measurements) {
  warning(
    warnedAboutGetMeasurementsSummaryMap,
    '`ReactPerf.getMeasurementsSummaryMap(...)` is deprecated. Use ' +
    '`ReactPerf.getWasted(...)` instead.'
  );
  warnedAboutGetMeasurementsSummaryMap = true;
  return getWasted(measurements);
}
function start() {