Add XPath test with a context node

ext/dom/tests/xpath_context_node.phpt

@@ -0,0 +1,31 @@
+--TEST--
+XPath: with a context node
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+$dom = new DOMDocument();
+$dom->loadXML(<<<XML
+<root>
+    <child>
+        <p>bar</p>
+    </child>
+    <child>
+        <p>foo1</p>
+        <p>foo2</p>
+    </child>
+</root>
+XML);
+$xpath = new DOMXpath($dom);
+
+foreach ($xpath->query("p", $dom->documentElement->firstElementChild->nextElementSibling) as $p) {
+    echo $p->textContent, "\n";
+}
+
+var_dump($xpath->evaluate("count(p)", $dom->documentElement->firstElementChild->nextElementSibling));
+
+?>
+--EXPECT--
+foo1
+foo2
+float(2)