[jsb] SocketIO client receives message twice

[dumganhar]

Reported at cocos/engine-native#563

• cocos2d-x version: v3.14.1
• devices test on: all
• developing environments
  • NDK version:
  • Xcode version:
  • VS version:
  • browser type and version:

Steps to Reproduce:

[PatriceJiang]

bug has been fixed before jul 10, 2017
cocos/scripting/js-bindings/manul/jsb_socketio.cpp

-    virtual void onMessage(SIOClient* client, const std::string& data)
+    virtual void onMessage(SIOClient* client, const std::string& data) override
     {
-        CCLOG("JSB SocketIO::SIODelegate->onMessage method called from native with data: %s", data.c_str());
-        this->fireEventToScript(client, "message", data);
     }
 

it is no longer exists in newer version. this issue should be closed, @minggo