Halogens have least priority in naming against other groups like -COOH,-CHO,-OH, etc. Hence to name the compound alphabetical order is used. Hence bromine gets it first preference followed by chlorine. But the suffix will be “ane”. One more thing to note is that carbon containing two chlorine atoms gets its first prefernce in numbering so that all substituents get least number. Hence its name would be 3-bromo 1,1,2 trichloro propane.