Fix #79271: DOMDocumentType::$childNodes is NULL

Dom level 2 core, DOM level 3 core and the DOM living standard agree
that `childNodes` always return a `NodeList`, and never `null`.

NEWS

@@ -12,6 +12,7 @@ PHP                                                                        NEWS
 - DOM:
   . Fixed bug #77569: (Write Access Violation in DomImplementation). (Nikita,
     cmb)
+  . Fixed bug #79271 (DOMDocumentType::$childNodes is NULL). (cmb)
 
 - PCRE:
   . Fixed bug #79188 (Memory corruption in preg_replace/preg_replace_callback

ext/dom/node.c

@@ -428,13 +428,9 @@ int dom_node_child_nodes_read(dom_object *obj, zval *retval)
 		return FAILURE;
 	}
 
-	if (dom_node_children_valid(nodep) == FAILURE) {
-		ZVAL_NULL(retval);
-	} else {
-		php_dom_create_interator(retval, DOM_NODELIST);
-		intern = Z_DOMOBJ_P(retval);
-		dom_namednode_iter(obj, XML_ELEMENT_NODE, intern, NULL, NULL, NULL);
-	}
+	php_dom_create_interator(retval, DOM_NODELIST);
+	intern = Z_DOMOBJ_P(retval);
+	dom_namednode_iter(obj, XML_ELEMENT_NODE, intern, NULL, NULL, NULL);
 
 	return SUCCESS;
 }

ext/dom/tests/bug69846.phpt

@@ -50,7 +50,7 @@ object(DOMText)#%d (19) {
   ["parentNode"]=>
   NULL
   ["childNodes"]=>
-  NULL
+  string(22) "(object value omitted)"
   ["firstChild"]=>
   NULL
   ["lastChild"]=>
@@ -140,7 +140,7 @@ object(DOMText)#%d (19) {
   ["parentNode"]=>
   NULL
   ["childNodes"]=>
-  NULL
+  string(22) "(object value omitted)"
   ["firstChild"]=>
   NULL
   ["lastChild"]=>

ext/dom/tests/bug79271.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Bug #79271 (DOMDocumentType::$childNodes is NULL)
+--SKIPIF--
+<?php
+if (!extension_loaded('dom')) die('skip dom extension not available');
+?>
+--FILE--
+<?php
+$dom = new DOMImplementation();
+$type = $dom->createDocumentType('html');
+var_dump($type->childNodes);
+?>
+--EXPECTF--
+object(DOMNodeList)#%d (1) {
+  ["length"]=>
+  int(0)
+}