when SIOClient::fireEvent the second time,crash.

[peter4431]

void SIOClient::fireEvent(const std::string& eventName, const std::string& data)
{
    CCLOGINFO("SIOClient::fireEvent called with event name: %s and data: %s", eventName.c_str(), data.c_str());

    _delegate->fireEventToScript(this, eventName, data);


    //if(_eventRegistry[eventName]) need to change
    if(_eventRegistry.find(eventName) != _eventRegistry.end())
    {
        SIOEvent e = _eventRegistry[eventName];

        e(this, data);

        return;
    }

    CCLOGINFO("SIOClient::fireEvent no native event with name %s found", eventName.c_str());
}