C++ properties of type QJSValue are not evaluated correctly

I have a C++ defined property of type QJSValue, and use it in the following QML:

Item {
    Foo {
        id: literal
        foo: [ { latitude: 5, longitude: 6 } ]
    }

    property variant coord1: QtLocation.coordinate(5, 6)

    Foo {
        id: prop
        foo: [ coord1 ]
    }

    Foo {
        id: func
        foo: [ QtLocation.coordinate(5, 6) ]
    }
}

Both the literal and prop objects are parsed as expected. For the func object in the foo setter I have verified that the value passed in is correct. I can use QJSValue::toString() to print out the correct value of each item in the array. However, QJSValue::toVariant() returns a QVariant containing a QVariantMap.

Changing the returned value of QJSValuePrivate::toVariant() from

return m_engine->variantFromJS(m_value);

to

return m_engine->toVariant(m_value, -1);

as suggested seems to fix the issue in this case.