chromium/third_party/blink/web_tests/storage/indexeddb/transaction-complete-workers.html

<html>
<head>
<script src="../../resources/js-test.js"></script>
<script src="resources/shared.js"></script>
</head>
<body>
<script>

worker = startWorker('resources/transaction-complete-workers.js');

// FIXME: It should be possible for the worker to set self.onerror to catch the event
// and call event.preventDefault(), but in the current Worker implementation the raw
// exception is seen by the event handler in the worker, not an ErrorEvent object.

var orig_onerror = worker.onerror;
worker.onerror = function (event) {
    if (event.message === "Uncaught Error: ignore this" || event.message === "Error: ignore this") {
        debug("Got expected error from worker, ignoring");
        evalAndLog("event.preventDefault()");
    } else if (orig_onerror) {
        orig_onerror(event);
    }
};


</script>
</body>
</html>