static void durationAttrSetter(v8::Local<v8::String> name, v8::Local<v8::Value> value, const v8::AccessorInfo& info)
{
    MediaSource* imp = V8MediaSource::toNative(info.Holder());
    double v = static_cast<double>(value->NumberValue());
    ExceptionCode ec = 0;
    imp->setDuration(v, ec);
    if (UNLIKELY(ec))
        setDOMException(ec, info.GetIsolate());
    return;
}