Have ElementTraversal / NodeTraversal's next() methods take a reference

Source/core/html/HTMLFormElement.h

Index: Source/core/html/HTMLFormElement.h
diff --git a/Source/core/html/HTMLFormElement.h b/Source/core/html/HTMLFormElement.h
index b547e58a93ef8dadfd3c48e1ef30a5ca808da2b3..b5c4ed68c6c158560075dbbfd29b33a8c4a44d78 100644
--- a/Source/core/html/HTMLFormElement.h
+++ b/Source/core/html/HTMLFormElement.h
@@ -65,7 +65,7 @@ public:
     bool shouldAutocomplete() const;
 
     // FIXME: Should rename these two functions to say "form control" or "form-associated element" instead of "form element".
-    void registerFormElement(FormAssociatedElement*);
+    void registerFormElement(FormAssociatedElement&);
     void removeFormElement(FormAssociatedElement*);
 
     void registerImgElement(HTMLImageElement*);
@@ -147,7 +147,7 @@ private:
     void scheduleFormSubmission(PassRefPtr<FormSubmission>);
 
     unsigned formElementIndexWithFormAttribute(Element*, unsigned rangeStart, unsigned rangeEnd);
-    unsigned formElementIndex(FormAssociatedElement*);
+    unsigned formElementIndex(FormAssociatedElement&);
 
     // Returns true if the submission should proceed.
     bool validateInteractively(Event*);