accounts/abi: remove deadcode isSigned (ethereum#16990)

accounts/abi/numbers.go

@@ -30,24 +30,9 @@ var (
 	uint16_t   = reflect.TypeOf(uint16(0))
 	uint32_t   = reflect.TypeOf(uint32(0))
 	uint64_t   = reflect.TypeOf(uint64(0))
-	int_t      = reflect.TypeOf(int(0))
 	int8_t     = reflect.TypeOf(int8(0))
 	int16_t    = reflect.TypeOf(int16(0))
 	int32_t    = reflect.TypeOf(int32(0))
 	int64_t    = reflect.TypeOf(int64(0))
 	address_t  = reflect.TypeOf(common.Address{})
-	int_ts     = reflect.TypeOf([]int(nil))
-	int8_ts    = reflect.TypeOf([]int8(nil))
-	int16_ts   = reflect.TypeOf([]int16(nil))
-	int32_ts   = reflect.TypeOf([]int32(nil))
-	int64_ts   = reflect.TypeOf([]int64(nil))
 )
-
-// checks whether the given reflect value is signed. This also works for slices with a number type
-func isSigned(v reflect.Value) bool {
-	switch v.Type() {
-	case int_ts, int8_ts, int16_ts, int32_ts, int64_ts, int_t, int8_t, int16_t, int32_t, int64_t:
-		return true
-	}
-	return false
-}