As can be seen from the first round of testing in PR #15864, trying to update Puppeteer beyond version `19.0.0` completely breaks testing in Firefox. Curiously it does work locally when the `--noChrome` flag is being used, so it seems to be an issue with running tests in both Chrome *and* Firefox in parallel.

We need to fix this, likely by making some adjustments to our test-suite, such that we don't get "stuck" on an older version of Puppeteer without being able to update. (A temporary work-around could also be to disable testing in Chrome.)

var manifest = JSON.parse(fs.readFileSync(options.manifestFile));
  const testFilter = options.testfilter.slice(0),
    xfaOnly = options.xfaOnly;
  if (testFilter.length || xfaOnly) {
    manifest = manifest.filter(function (item) {
      var i = testFilter.indexOf(item.id);
      if (i !== -1) {
        testFilter.splice(i, 1);
        return true;
      }
      if (xfaOnly && item.enableXfa) {
        return true;
      }
      return false;
    });
    if (testFilter.length) {
      console.error("Unrecognized test IDs: " + testFilter.join(" "));
      return undefined;
    }
  }
  return manifest;
}
function checkEq(task, results, browser, masterMode) {