Fix incorrect output from JSON.stringify

This patch fixes the #2383 issue

JerryScript-DCO-1.0-Signed-off-by: Istvan Miklos imiklos2@inf.u-szeged.hu

Author: Istvan Miklos

jerry-ext/handler/handler-print.c

@@ -65,7 +65,7 @@ jerryx_handler_print (const jerry_value_t func_obj_val, /**< function object */
       jerry_length_t substr_pos = 0;
       jerry_char_t substr_buf[256];
 
-      while ((substr_size = jerry_substring_to_char_buffer (str_val,
+      while ((substr_size = jerry_substring_to_utf8_char_buffer (str_val,
                                                             substr_pos,
                                                             substr_pos + 256,
                                                             substr_buf,