Fix DocumentFragment ownerDocument

Author: henrytao-me

.changeset/pretty-bags-cheer.md

@@ -0,0 +1,6 @@
+---
+'@remote-dom/polyfill': patch
+'@remote-dom/core': patch
+---
+
+Fix document fragment owner document

packages/polyfill/source/DocumentFragment.ts

@@ -4,5 +4,7 @@ import {ParentNode} from './ParentNode.ts';
 export class DocumentFragment extends ParentNode {
   nodeType = NodeType.DOCUMENT_FRAGMENT_NODE;
   [NAME] = '#document-fragment';
-  [OWNER_DOCUMENT] = window.document as any;
+  [OWNER_DOCUMENT] = (typeof window !== 'undefined'
+    ? window.document
+    : null) as any;
 }