NEW YORK — McDonald's is expanding sales of its meatless McPlant burger to hundreds of locations. The company said the McPlant — which it co-developed with plant-based protein company Beyond Meat — will be sold at 600 stores in the San Francisco and Dallas areas starting Feb. 14. It's a major expansion for the McPlant, which was introduced last November at eight stores in Texas, Iowa, Louisiana and California. That test run helped the company determine how a plant-based option would alter its kitchen operations. McDonald's said the larger product offering will help it understand customer demand. The Chicago company…