chromium/third_party/blink/web_tests/wpt_internal/speech/scripted/start-multiple.html

<!doctype html>
<title>Verify that multiple SpeechRecognition objects can co-exist in tests</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script type="module">
import {MockSpeechRecognizer} from '../resources/mock-speechrecognizer.js';

const mock = new MockSpeechRecognizer();

async_test(t => {
  const objectCount = 4;
  let count = objectCount;

  for (let i = 0; i < objectCount; ++i) {
      const recog = new webkitSpeechRecognition();
      recog.onend = t.step_func(() => {
          if (--count == 0)
              t.done();
      });
      recog.start();
  }
});
</script>