TIJUANA — In her first moments back in Mexico after more than 30 years away, Dulce Garcia laughed at how easily she was able to cross south. It was a moment that Garcia thought would not be possible. It was also a moment she feared. Garcia, 38, has lived most of her life as an immigrant illegally in the United States. Under normal circumstances, if she went to Mexico, she would not be able to return to her home in San Diego. Because she came to the United States at age 4, she was able to enroll in the Deferred Action for Childhood Arrivals, or DACA, which temporarily shields so-called Dre...