Fixes MSVC casting warning.
Fixes MSVC casting warning.

goby/googletest,gclone/googletest,dpull/googletest,amitkr/googletest,gclone/googletest,amitkr/googletest,gclone/googletest,marcossilvadecastro/googletest,BeeswaxIO/googletest,Perfexion/googletest,BeeswaxIO/googletest,osamu0329nakamura/googletest,dpull/googletest,BeeswaxIO/googletest,amitkr/googletest,osamu0329nakamura/googletest,dpull/googletest,marcossilvadecastro/googletest,old8xp/googletest-from-google,osamu0329nakamura/googletest,marcossilvadecastro/googletest,old8xp/googletest-from-google,goby/googletest,Perfexion/googletest,old8xp/googletest-from-google,goby/googletest,Perfexion/googletest,marcossilvadecastro/googletest