I’m travelling at the moment, and unable to research the issue properly, but I couldn’t help noticing that there’s a certain amount of concern that the WebGL graphics engine may expose the user of browsers in which it is enabled to a number of risks: see, for instance, Dan Goodin’s article http://www.theregister.co.uk/2011/05/11/chrome_firefox_security_threat/.
In fact, it appears that US-CERT is advising Firefox and Chrome users to disable it, and the article in the Register does tell you how, should you wish to. Rob Slade also raised the issue on a security list as regards other browsers, notably Safari. I’m not in a position to assess the risk right now on any platform, but if you want to play safe, I note that this article gives instructions for enabling WebGL on Safari and Chromium. I guess you can work out how to disable it from that, but I only have smartphone access right now, so not able to check myself.