Fix leak when setting dynamic property on generator

Author: nikic

Zend/tests/generators/dynamic_properties.phpt

@@ -9,7 +9,7 @@ function gen() {
 
 $gen = gen();
 try {
-    $gen->prop = 42;
+    $gen->prop = new stdClass;
 } catch (Error $e) {
     echo $e->getMessage(), "\n";
 }

Zend/zend_object_handlers.c

@@ -772,11 +772,10 @@ ZEND_API zval *zend_std_write_property(zend_object *zobj, zend_string *name, zva
 	} else {
 		ZEND_ASSERT(!IS_WRONG_PROPERTY_OFFSET(property_offset));
 write_std_property:
-		Z_TRY_ADDREF_P(value);
 		if (EXPECTED(IS_VALID_PROPERTY_OFFSET(property_offset))) {
-
 			variable_ptr = OBJ_PROP(zobj, property_offset);
 
+			Z_TRY_ADDREF_P(value);
 			if (UNEXPECTED(prop_info)) {
 				ZVAL_COPY_VALUE(&tmp, value);
 				if (UNEXPECTED(!zend_verify_property_type(prop_info, &tmp, property_uses_strict_types()))) {
@@ -794,6 +793,8 @@ ZEND_API zval *zend_std_write_property(zend_object *zobj, zend_string *name, zva
 				variable_ptr = &EG(error_zval);
 				goto exit;
 			}
+
+			Z_TRY_ADDREF_P(value);
 			if (!zobj->properties) {
 				rebuild_object_properties(zobj);
 			}