Fix dom_import_simplexml()

stubs/extensions/dom.phpstub

@@ -50,10 +50,6 @@ const DOM_NAMESPACE_ERR = 14;
 const DOM_INVALID_ACCESS_ERR = 15;
 const DOM_VALIDATION_ERR = 16;
 
-function dom_import_simplexml(object $node): ?DOMElement {}
-/** @php-from 8.0 */
-function dom_import_simplexml(object $node): DOMElement {}
-
 final class DOMException extends Exception
 {
     public int $code;

tests/ExtLibxmlStubTest.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psalm\Tests;
+
+use Psalm\Tests\Traits\ValidCodeAnalysisTestTrait;
+
+class ExtLibxmlStubTest extends TestCase
+{
+    use ValidCodeAnalysisTestTrait;
+
+    public function providerValidCodeParse(): iterable
+    {
+        return [
+            'dom_import_simplexml, php >=8.0' => [
+                'code' => <<<'PHP'
+                    <?php
+                    $x = dom_import_simplexml(new SimpleXMLElement(''));
+                    PHP,
+                'assertions' => ['$x===' => 'DOMElement'],
+                'ignored_issues' => [],
+                'php_version' => '8.0',
+            ],
+            'dom_import_simplexml, php <8.0' => [
+                'code' => <<<'PHP'
+                    <?php
+                    $x = dom_import_simplexml(new SimpleXMLElement(''));
+                    PHP,
+                'assertions' => ['$x===' => 'DOMElement|null'],
+                'ignored_issues' => [],
+                'php_version' => '7.4',
+            ],
+        ];
+    }
+}