json: use `write_char c` instead of `write c.to_s`

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/lib/json/serialization_write.nit b/lib/json/serialization_write.nit
index 43987e8..e226e30 100644 (file)
--- a/lib/json/serialization_write.nit
+++ b/lib/json/serialization_write.nit
@@ -161,7 +161,7 @@ redef class Text
                                        v.stream.write char.escape_to_utf16
                                end
                        else
-                               v.stream.write char.to_s
+                               v.stream.write_char char
                        end
                end
                v.stream.write "\""