HAVANA - It was supposed to be the ultimate tribute, several days of parties and concerts to mark Fidel Castro's 80th birthday. But instead of listening to folk music and attending conferences on his legacy, Castro is expected to spend his birthday Sunday in bed, recovering from surgery for intestinal bleeding. Cubans have cultivated a myth over the last half-century that Castro is invincible, but now confront the fact that he is an octogenarian — and frail like other elderly mortals. A few Cubans say it won't be long before Castro is giving five-hour speeches once again, but many believe...