Fixes to attributes in Node::isEqualNode

lib/Node.php

@@ -1061,8 +1061,12 @@ abstract class Node implements \Stringable {
             # • If A is an element, each attribute in its attribute list has an attribute that
             #   equals an attribute in B’s attribute list.
             $thisNodeAttributes = $thisNode->attributes;
-            foreach ($thisNodeAttributes as $key => $attr) {
-                if (!$this->isEqualInnerNode($attr, $otherAttributes[$key])) {
+            foreach ($thisNodeAttributes as $attr) {
+                if (!($otherAttr = $otherNode->getAttributeNodeNS($attr->namespaceURI, $attr->name))) {
+                    return false;
+                }
+
+                if (!$this->isEqualInnerNode($attr, $otherAttr)) {
                     return false;
                 }
             }

tests/cases/TestNode.php

@@ -378,6 +378,11 @@ class TestNode extends \PHPUnit\Framework\TestCase {
         $this->assertFalse($html->isEqualNode($html2));
         $html->appendChild($body);
         $this->assertFalse($html->isEqualNode($html2));
+        $html = $d->createElement('html');
+        $html->setAttribute('id', 'ook');
+        $html2 = $d->createElement('html');
+        $html2->setAttribute('class', 'ook');
+        $this->assertFalse($html->isEqualNode($html2));
 
         // Different text nodes
         $this->assertFalse($d->createTextNode('ook')->isEqualNode($d->createTextNode('eek')));