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

accounts/abi/numbers.go

@@ -30,24 +30,9 @@ var (
 	uint16T   = reflect.TypeOf(uint16(0))
 	uint32T   = reflect.TypeOf(uint32(0))
 	uint64T   = reflect.TypeOf(uint64(0))
-	intT      = reflect.TypeOf(int(0))
 	int8T     = reflect.TypeOf(int8(0))
 	int16T    = reflect.TypeOf(int16(0))
 	int32T    = reflect.TypeOf(int32(0))
 	int64T    = reflect.TypeOf(int64(0))
 	addressT  = reflect.TypeOf(common.Address{})
-	intTS     = reflect.TypeOf([]int(nil))
-	int8TS    = reflect.TypeOf([]int8(nil))
-	int16TS   = reflect.TypeOf([]int16(nil))
-	int32TS   = reflect.TypeOf([]int32(nil))
-	int64TS   = 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 intTS, int8TS, int16TS, int32TS, int64TS, intT, int8T, int16T, int32T, int64T:
-		return true
-	}
-	return false
-}