I'm using the onboard/ondie Intel HD4000 and it works. You might have a driver that is blacklisted. Chrome and I think other browsers have a list of drivers kno

I'm using the onboard/ondie Intel HD4000 and it works. You might have a driver that is blacklisted. Chrome and I think other browsers have a list of drivers known to allow execution of dangerous shader code and block WebGL in those cases.