Feb 24 (Reuters) - Overview -- Seattle-based coffeehouse company Starbucks Corp.'s profitability gains continue to propel improvement in credit measures. -- We anticipate expansion in international markets and product innovation will continue to boost profit growth. -- We are raising our corporate credit rating on Starbucks to 'A-' from 'BBB+'. -- The outlook is stable, reflecting our expectation for further EBITDA gains and modest improvement of credit measu