Two new anchor stores are moving into the Willow Grove Park Mall, in a long-vacant three-story space once occupied by Strawbridge’s. They are JC Penney and Nordstrom Rack, the off-price clearance division of the upscale Nordstrom Department Stores.  The 190,000-square-foot space will be completely renovated, and the stores should open next year.  The company that owns the mall, Pennsylvania Real Estate Development Trust, says the new stores will make Willow Grove more competitive with the larger malls including the one in King of Prussia, which is owned by a different company.