That's something that the web site in question might provide--in your case Yahoo! If it's not there, then the web site decided to not have that option (any more perhaps).
Generally doesn't have much to do with the browser used. That said, just to try it out, have you tried some other browsers like Google Chrome or Dolphin or any other ones to see if that link appears in those somehow? (And on that topic, a lot of third party browsers have a native option in settings to request a desktop version of the web site.)