Add a regression test for phpGH-10234

Co-authored-by: ThomasWeinert <[email protected]>

Author: nielsdos

ext/dom/tests/gh10234.phpt

@@ -0,0 +1,22 @@
+--TEST--
+GH-10234 (Setting DOMAttr::textContent results in an empty attribute value.)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+$document = new DOMDocument();
+$document->loadXML('<element attribute="value"/>');
+$attribute = $document->documentElement->getAttributeNode('attribute');
+
+// output loaded attribute value
+var_dump($attribute->textContent);
+
+// change value
+$attribute->textContent = 'new value';
+
+// output changed value
+var_dump($attribute->textContent);
+?>
+--EXPECT--
+string(5) "value"
+string(9) "new value"