Pass implementation object to supplemental classes by reference

Source/core/xml/DocumentXPathEvaluator.h

Index: Source/core/xml/DocumentXPathEvaluator.h
diff --git a/Source/core/xml/DocumentXPathEvaluator.h b/Source/core/xml/DocumentXPathEvaluator.h
index 04a39f93dbb0f1bb8cf066212969d3e74bb75b1c..adf35d15619c1af12e2a88fbf0f1e7ca2eb24fc0 100644
--- a/Source/core/xml/DocumentXPathEvaluator.h
+++ b/Source/core/xml/DocumentXPathEvaluator.h
@@ -40,12 +40,12 @@ class DocumentXPathEvaluator FINAL : public DocumentSupplement {
 public:
     virtual ~DocumentXPathEvaluator();
 
-    static DocumentXPathEvaluator* from(DocumentSupplementable*);
+    static DocumentXPathEvaluator& from(DocumentSupplementable&);
 
-    static PassRefPtr<XPathExpression> createExpression(DocumentSupplementable*,
+    static PassRefPtr<XPathExpression> createExpression(DocumentSupplementable&,
         const String& expression, PassRefPtr<XPathNSResolver>, ExceptionState&);
-    static PassRefPtr<XPathNSResolver> createNSResolver(DocumentSupplementable*, Node* nodeResolver);
-    static PassRefPtr<XPathResult> evaluate(DocumentSupplementable*,
+    static PassRefPtr<XPathNSResolver> createNSResolver(DocumentSupplementable&, Node* nodeResolver);
+    static PassRefPtr<XPathResult> evaluate(DocumentSupplementable&,
         const String& expression, Node* contextNode, PassRefPtr<XPathNSResolver>,
         unsigned short type, XPathResult*, ExceptionState&);