Have Node::document() return a reference instead of a pointer

Source/core/xml/XSLTProcessorLibxslt.cpp

Index: Source/core/xml/XSLTProcessorLibxslt.cpp
diff --git a/Source/core/xml/XSLTProcessorLibxslt.cpp b/Source/core/xml/XSLTProcessorLibxslt.cpp
index 74fcf53a1aae71eb09695a452678c92b4f8483e8..6f86926eae71ba6c2feb10e368db5f772780ad8a 100644
--- a/Source/core/xml/XSLTProcessorLibxslt.cpp
+++ b/Source/core/xml/XSLTProcessorLibxslt.cpp
@@ -226,8 +226,8 @@ static xsltStylesheetPtr xsltStylesheetPointer(RefPtr<XSLStyleSheet>& cachedStyl
 {
     if (!cachedStylesheet && stylesheetRootNode) {
         cachedStylesheet = XSLStyleSheet::createForXSLTProcessor(stylesheetRootNode->parentNode() ? stylesheetRootNode->parentNode() : stylesheetRootNode,
-            stylesheetRootNode->document()->url().string(),
-            stylesheetRootNode->document()->url()); // FIXME: Should we use baseURL here?
+            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.
@@ -242,7 +242,7 @@ static xsltStylesheetPtr xsltStylesheetPointer(RefPtr<XSLStyleSheet>& cachedStyl
 
 static inline xmlDocPtr xmlDocPtrFromNode(Node* sourceNode, bool& shouldDelete)
 {
-    RefPtr<Document> ownerDocument = sourceNode->document();
+    RefPtr<Document> ownerDocument = &sourceNode->document();
     bool sourceIsDocument = (sourceNode == ownerDocument.get());
 
     xmlDocPtr sourceDoc = 0;
@@ -277,7 +277,7 @@ static inline String resultMIMEType(xmlDocPtr resultDoc, xsltStylesheetPtr sheet
 
 bool XSLTProcessor::transformToString(Node* sourceNode, String& mimeType, String& resultString, String& resultEncoding)
 {
-    RefPtr<Document> ownerDocument = sourceNode->document();
+    RefPtr<Document> ownerDocument = &sourceNode->document();
 
     setXSLTLoadCallBack(docLoaderFunc, this, ownerDocument->fetcher());
     xsltStylesheetPtr sheet = xsltStylesheetPointer(m_stylesheet, m_stylesheetRootNode.get());