Fix JSON::Coder to call as_json proc for NaN and Infinity

Co-authored-by: Jean Boussier <jean.boussier@gmail.com>

Author: etiennebarrie

ext/json/ext/generator/generator.c

@@ -1031,13 +1031,19 @@ static void generate_json_float(FBuffer *buffer, struct generate_json_data *data
 {
     double value = RFLOAT_VALUE(obj);
     char allow_nan = state->allow_nan;
-    VALUE tmp = rb_funcall(obj, i_to_s, 0);
     if (!allow_nan) {
         if (isinf(value) || isnan(value)) {
-            raise_generator_error(obj, "%"PRIsVALUE" not allowed in JSON", tmp);
+            if (state->strict && state->as_json) {
+                obj = rb_proc_call_with_block(state->as_json, 1, &obj, Qnil);
+                state->depth++;
+                generate_json(buffer, data, state, obj);
+                state->depth--;
+                return;
+            }
+            raise_generator_error(obj, "%"PRIsVALUE" not allowed in JSON", rb_funcall(obj, i_to_s, 0));
         }
     }
-    fbuffer_append_str(buffer, tmp);
+    fbuffer_append_str(buffer, rb_funcall(obj, i_to_s, 0));
 }
 
 static void generate_json_fragment(FBuffer *buffer, struct generate_json_data *data, JSON_Generator_State *state, VALUE obj)