XSLImportRule should not be ResourceClient.

Source/core/xml/XSLTProcessorLibxslt.cpp

 /*
  * This file is part of the XSL implementation.
  *
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple, Inc. All rights reserved.
  * Copyright (C) 2005, 2006 Alexey Proskuryakov <ap@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 200 matching lines @@
     if (!params)
         return;
 
     while (*temp) {
         fastFree(const_cast<char*>(*(temp++)));
         fastFree(const_cast<char*>(*(temp++)));
     }
     fastFree(params);
 }
 
-static xsltStylesheetPtr xsltStylesheetPointer(RefPtrWillBeMember<XSLStyleSheet>& cachedStylesheet, Node* stylesheetRootNode)
+static xsltStylesheetPtr xsltStylesheetPointer(Document* document, RefPtrWillBeMember<XSLStyleSheet>& cachedStylesheet, Node* stylesheetRootNode)
 {
     if (!cachedStylesheet && stylesheetRootNode) {
+        // When using importStylesheet, we will use the given document as the imported stylesheet's owner.
         cachedStylesheet = XSLStyleSheet::createForXSLTProcessor(
-            stylesheetRootNode->parentNode() ? stylesheetRootNode->parentNode() : stylesheetRootNode,
+            stylesheetRootNode->parentNode() ? &stylesheetRootNode->parentNode()->document() : document,
+            stylesheetRootNode,
             stylesheetRootNode->document().url().string(),
             stylesheetRootNode->document().url()); // FIXME: Should we use baseURL here?
 
         // According to Mozilla documentation, the node must be a Document node,
         // an xsl:stylesheet or xsl:transform element. But we just use text
         // content regardless of node type.
         cachedStylesheet->parseString(createMarkup(stylesheetRootNode));
     }
 
     if (!cachedStylesheet || !cachedStylesheet->document())
@@ skipping 35 matching lines @@
         return "text/plain";
 
     return "application/xml";
 }
 
 bool XSLTProcessor::transformToString(Node* sourceNode, String& mimeType, String& resultString, String& resultEncoding)
 {
     RefPtrWillBeRawPtr<Document> ownerDocument(sourceNode->document());
 
     setXSLTLoadCallBack(docLoaderFunc, this, ownerDocument->fetcher());
-    xsltStylesheetPtr sheet = xsltStylesheetPointer(m_stylesheet, m_stylesheetRootNode.get());
+    xsltStylesheetPtr sheet = xsltStylesheetPointer(m_document.get(), m_stylesheet, m_stylesheetRootNode.get());
     if (!sheet) {
         setXSLTLoadCallBack(0, 0, 0);
         m_stylesheet = nullptr;
         return false;
     }
     m_stylesheet->clearDocuments();
 
     xmlChar* origMethod = sheet->method;
     if (!origMethod && mimeType == "text/html")
         sheet->method = (xmlChar*)"html";
@@ skipping 51 matching lines @@
 
     sheet->method = origMethod;
     setXSLTLoadCallBack(0, 0, 0);
     xsltFreeStylesheet(sheet);
     m_stylesheet = nullptr;
 
     return success;
 }
 
 } // namespace blink