LOS ANGELES- Florencia Molina's personal hellhole was a dressmaking shop on the outskirts of Los Angeles. She worked there up to 17 hours a day, seven days a week, and lived there, too, without the option of showering or washing her clothes. Other victims of American-style human trafficking have had very different venues for ordeals as bad or worse _ brothels and bars in New Jersey, slave-labor farms in Florida, a small-town tree-cutting business owned by a New Hampshire couple. Trafficking is a stubborn problem and a staggering one worldwide, affecting an estimated 600,000 to 800,000 victims a year. Federal...