To support WebGl (or Hardware accelleration) browser must ensure compatibility with Video card drivers. This is done per card / per driver revision / per OS version (because they can be quite different).
The message that you are getting just means that your combination of Operating System, Graphic Card and Video Driver is not supported by Opera (yet). This might or might not change in future.
but it works in Chrome
- all browsers are different ;) Especially in implementations of such experimental features as WebGL.