OSLO, Norway — Arab Spring or European Union? Speculation ahead of the Nobel Peace Prize announcement on Friday is split after cryptic comments by the award committee’s chairman. Many Nobel watchers have seen the revolutions against autocratic regimes in North Africa and the Middle East as the most likely subject of this year’s prize. An American professor who wrote a guide to nonviolent protests was a bookmaker’s favorite Thursday. But Norway’s TV2 expected the prize to go to Liberian President Ellen Johnson Sirleaf, while remarks by Thorbjoern Jagland, who has led the five-member Norwegian panel since 2009, have fueled speculation the prize could go to the EU….