Have ElementTraversal::firstWithin() take a reference

Source/core/html/HTMLFieldSetElement.cpp

Index: Source/core/html/HTMLFieldSetElement.cpp
diff --git a/Source/core/html/HTMLFieldSetElement.cpp b/Source/core/html/HTMLFieldSetElement.cpp
index 7973ee6a5a1099ef05b64eef4a7689cc9939bfb2..cb9074cc0cb8932c4a40b1ec6b8eaae9d7cc7f32 100644
--- a/Source/core/html/HTMLFieldSetElement.cpp
+++ b/Source/core/html/HTMLFieldSetElement.cpp
@@ -49,9 +49,9 @@ PassRefPtr<HTMLFieldSetElement> HTMLFieldSetElement::create(Document& document,
     return adoptRef(new HTMLFieldSetElement(document, form));
 }
 
-void HTMLFieldSetElement::invalidateDisabledStateUnder(Element* base)
+void HTMLFieldSetElement::invalidateDisabledStateUnder(Element& base)
 {
-    for (Element* element = ElementTraversal::firstWithin(base); element; element = ElementTraversal::next(*element, base)) {
+    for (Element* element = ElementTraversal::firstWithin(base); element; element = ElementTraversal::next(*element, &base)) {
         if (element->isFormControlElement())
             toHTMLFormControlElement(element)->ancestorDisabledStateWasChanged();
     }
@@ -61,15 +61,15 @@ void HTMLFieldSetElement::disabledAttributeChanged()
 {
     // This element must be updated before the style of nodes in its subtree gets recalculated.
     HTMLFormControlElement::disabledAttributeChanged();
-    invalidateDisabledStateUnder(this);
+    invalidateDisabledStateUnder(*this);
 }
 
 void HTMLFieldSetElement::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
 {
     HTMLFormControlElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
-    for (Element* element = ElementTraversal::firstWithin(this); element; element = ElementTraversal::nextSkippingChildren(element, this)) {
+    for (Element* element = ElementTraversal::firstWithin(*this); element; element = ElementTraversal::nextSkippingChildren(element, this)) {
         if (element->hasTagName(legendTag))
-            invalidateDisabledStateUnder(element);
+            invalidateDisabledStateUnder(*element);
     }
 }
 
@@ -91,7 +91,7 @@ RenderObject* HTMLFieldSetElement::createRenderer(RenderStyle*)
 
 HTMLLegendElement* HTMLFieldSetElement::legend() const
 {
-    for (Element* child = ElementTraversal::firstWithin(this); child; child = ElementTraversal::nextSkippingChildren(child, this)) {
+    for (Element* child = ElementTraversal::firstWithin(*this); child; child = ElementTraversal::nextSkippingChildren(child, this)) {
         if (child->hasTagName(legendTag))
             return toHTMLLegendElement(child);
     }
@@ -113,7 +113,7 @@ void HTMLFieldSetElement::refreshElementsIfNeeded() const
 
     m_associatedElements.clear();
 
-    for (Element* element = ElementTraversal::firstWithin(this); element; element = ElementTraversal::next(*element, this)) {
+    for (Element* element = ElementTraversal::firstWithin(*this); element; element = ElementTraversal::next(*element, this)) {
         if (element->hasTagName(objectTag)) {
             m_associatedElements.append(toHTMLObjectElement(element));
             continue;