[QWebChannel] Cannot use simple JavaScript objects as parameters to methods invoked via a QWebChannel

function runTest() {
        var _ = new QWebChannel(qt.webChannelTransport, function(channel) {
                var obj = { "testObject": "yes" };
                channel.objects.proxy.logVariant(obj);
                channel.objects.proxy.logJSONValue(obj);
                channel.objects.proxy.logJSONObject(obj);
                channel.objects.proxy.logString(JSON.stringify(obj));
        });
        document.write("Loaded!");
}

Q_INVOKABLE void logVariant(const QVariant &val);
Q_INVOKABLE void logJSONValue(const QJsonValue &val);
Q_INVOKABLE void logJSONObject(const QJsonObject &val);
Q_INVOKABLE void logString(const QString &val);

void WebProxy::logVariant(const QVariant &val)
{
	qDebug() << "VARIANT VAL:" << val.toJsonValue();
	qDebug() << "VARIANT OBJ:" << val.toJsonObject();
}

void WebProxy::logJSONValue(const QJsonValue &val)
{
	qDebug() << "JSON VALUE:" << val;
}

void WebProxy::logJSONObject(const QJsonObject &val)
{
	qDebug() << "JSON OBJECT:" << val;
}

void WebProxy::logString(const QString &val)
{
	qDebug() << "STRING:" << val;
}