Coming into the 4th of July weekend, “Transformers: Revenge of the Fallen” was on a rampage at the box office, amassing $200 million in five days. Given the abysmal reviews, this surprised a lot of people, yours truly included. But word of mouth must have trickled down, because “Transformers” dropped 61 percent and barely edged out “Ice Age: Dawn of the Dinosaurs” for first place with $42.4 million. In fact, it was so close, weekend estimates had the two films …