As mentioned in an older post, there are several ways to enable WebGL/ X3DOM support on iOS. The good news here is that with an upgrade to iOS 6.0.1 or 6.1 X3DOM now works again smoothly, so there is no more need to stick to iOS 5…
Generally, while the official WebKit implementation on iOS includes WebGL, it is not activated by default. The standard Safari browser hence does not yet support WebGL. Therefore, we wrote our own instantGLory App (which basically is a wrapper around the WebView widget), and there are other solutions around.