Revert gojson changes

gojson/decode_test.go

@@ -108,11 +108,11 @@ func (u unmarshalerText) MarshalText() ([]byte, error) {
 }
 
 func (u *unmarshalerText) UnmarshalText(b []byte) error {
-	before, after, ok := bytes.Cut(b, []byte{':'})
-	if !ok {
+	pos := bytes.IndexByte(b, ':')
+	if pos == -1 {
 		return errors.New("missing separator")
 	}
-	u.A, u.B = string(before), string(after)
+	u.A, u.B = string(b[:pos]), string(b[pos+1:])
 	return nil
 }
 
@@ -126,7 +126,7 @@ type ustructText struct {
 type u8marshal uint8
 
 func (u8 u8marshal) MarshalText() ([]byte, error) {
-	return fmt.Appendf(nil, "u%d", u8), nil
+	return []byte(fmt.Sprintf("u%d", u8)), nil
 }
 
 var errMissingU8Prefix = errors.New("missing 'u' prefix")
@@ -275,7 +275,7 @@ func (unexportedWithMethods) F() {}
 type byteWithMarshalJSON byte
 
 func (b byteWithMarshalJSON) MarshalJSON() ([]byte, error) {
-	return fmt.Appendf(nil, `"Z%.2x"`, byte(b)), nil
+	return []byte(fmt.Sprintf(`"Z%.2x"`, byte(b))), nil
 }
 
 func (b *byteWithMarshalJSON) UnmarshalJSON(data []byte) error {
@@ -303,7 +303,7 @@ func (b *byteWithPtrMarshalJSON) UnmarshalJSON(data []byte) error {
 type byteWithMarshalText byte
 
 func (b byteWithMarshalText) MarshalText() ([]byte, error) {
-	return fmt.Appendf(nil, `Z%.2x`, byte(b)), nil
+	return []byte(fmt.Sprintf(`Z%.2x`, byte(b))), nil
 }
 
 func (b *byteWithMarshalText) UnmarshalText(data []byte) error {
@@ -331,7 +331,7 @@ func (b *byteWithPtrMarshalText) UnmarshalText(data []byte) error {
 type intWithMarshalJSON int
 
 func (b intWithMarshalJSON) MarshalJSON() ([]byte, error) {
-	return fmt.Appendf(nil, `"Z%.2x"`, int(b)), nil
+	return []byte(fmt.Sprintf(`"Z%.2x"`, int(b))), nil
 }
 
 func (b *intWithMarshalJSON) UnmarshalJSON(data []byte) error {
@@ -359,7 +359,7 @@ func (b *intWithPtrMarshalJSON) UnmarshalJSON(data []byte) error {
 type intWithMarshalText int
 
 func (b intWithMarshalText) MarshalText() ([]byte, error) {
-	return fmt.Appendf(nil, `Z%.2x`, int(b)), nil
+	return []byte(fmt.Sprintf(`Z%.2x`, int(b))), nil
 }
 
 func (b *intWithMarshalText) UnmarshalText(data []byte) error {