Are you trying to call to your game server? Looks like a cross site scripting issue - have you configured CORS on your server?
No i did not i use uMMORPG but also i contacted him as well and he told me there is no issue with WebGL for this i dont know how to fix this issue they say its Unity problem build dont know
Ok i get it the error its HTTPS security it wont allow connection on non secure connection I think i have to do that but dont know how to :/ the Unity shell have take that in mind to add a option or something to this