It's hard to help unless you describe exactly what is happening - what exactly are you seeing when you say it crashes?
If it works on iOS 9 it could be an iOS bug which was subsequently fixed, in which case there's nothing that can be done other than updating the device. Apple's stats say 85% of users are already on iOS 9 so this would only affect a minority of users. Also if the device hasn't got much memory then maybe it's running out.
Thanks for the quick reply.Well most times the games doesn't go past the loader,the whole browser crashes.It happens on chrome,firefox and safari running on IOS 8 device.Some times,it does load ,but crashes randomly in some other places,by exiting/closing the browser itself. So your saying apart from IOS 8 bugs ,it could also be an running out of memory problem.Mostly the browser just crashes or closes when these crashes occurs.