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

Source/core/xml/XPathExpression.cpp

Index: Source/core/xml/XPathExpression.cpp
diff --git a/Source/core/xml/XPathExpression.cpp b/Source/core/xml/XPathExpression.cpp
index 0850a92a65d5bda768379708eca36b07dfc2daeb..920f6c93c87c151e0c6f54d9cfa389fe129752dd 100644
--- a/Source/core/xml/XPathExpression.cpp
+++ b/Source/core/xml/XPathExpression.cpp
@@ -69,7 +69,7 @@ PassRefPtr<XPathResult> XPathExpression::evaluate(Node* contextNode, unsigned sh
     evaluationContext.size = 1;
     evaluationContext.position = 1;
     evaluationContext.hadTypeConversionError = false;
-    RefPtr<XPathResult> result = XPathResult::create(contextNode->document(), m_topExpression->evaluate());
+    RefPtr<XPathResult> result = XPathResult::create(&contextNode->document(), m_topExpression->evaluate());
     evaluationContext.node = 0; // Do not hold a reference to the context node, as this may prevent the whole document from being destroyed in time.
 
     if (evaluationContext.hadTypeConversionError) {