DUBAI, United Arab Emirates — The Burj Dubai skyscraper under construction here reached its 100th story on Tuesday, nearly two-thirds of the way in its relentless climb to become the world's tallest building. With 3,000 laborers adding a new floor nearly every three days, the $1 billion spire is at 1,140 feet and days away from surpassing a neighboring skyscraper, the razor-blade resembling Emirates Office Tower, at 1,165 feet. The Emirates Office Tower is currently the tallest in the Middle East, Dubai-based developer Emaar Properties said. "The tower is a symbol of the city's pride and a statement of our...