Bugs like

void setWheelEventMonitorTestCallbackAndStartMonitoring(bool expectWheelEndOrCancel, bool expectMomentumEnd, WebCore::Frame& frame, JSContextRef context, JSObjectRef jsCallbackFunction)
{
    Page* page = frame.page();
    if (!page || !page->isMonitoringWheelEvents())
        return;

    JSValueProtect(context, jsCallbackFunction);

    if (auto wheelEventTestMonitor = page->wheelEventTestMonitor()) {
        wheelEventTestMonitor->setTestCallbackAndStartMonitoring(expectWheelEndOrCancel, expectMomentumEnd, [=](void) {
            JSObjectCallAsFunction(context, jsCallbackFunction, nullptr, 0, nullptr, nullptr);
            JSValueUnprotect(context, jsCallbackFunction);
        });
    }
}

<rdar://problem/92513529>