by David Frane Not long ago, I was on a crew completing a house frame when the backhoe operator cut the power line. With no juice to run saws, everyone spent the next few hours pushing brooms and moving piles of stock. Everyone, that is, except the guy I was working with: He pulled out a cordless circular saw and kept on going. Cordless drills are so common that a tradesperson who doesn't have one gets funny looks from his coworkers. But cordless circular saws are another story. They've been available for more than 10 years, but I haven't seen many on job sites. Last spring, DeWalt unveiled a line of 18-volt cordless tools, including a circular saw —