This, for the most part, is not possible. You can potentially grab a still image of the web page you are looking for and use it as a texture, but to actually use it like you would in an actual web browser, it's not quite possible.
Also, remember the difference- A web browser displays HTML pages. What you are looking for is something in Unity to render that HTML page to a texture on a mesh in game.
answered Jun 20 '12 at 10:33 AM