BANGKOK, Dec 3 (Reuters) - Thailand's benchmark index ended marginally higher on Thursday weighed down by selloffs in shares of CP All, while most others in Southeast Asia were range-bound ahead of the European Central Bank's policy decision. Bangkok's SET index was up 0.09 percent, reversing earlier falls to the lowest since Aug. 26. Recently-battered large-caps such as Advanced Info Service and Siam Cement led the rebound. Shares of retailer CP All dropped more than 5 percent, the wor
