Have ElementData::attributeItem() return a reference

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index 781d8f1c2c902f0888f0b3f642e2f65c55f5da87..ae6a107791e2c3a5fede2f8374814286d68913f1 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -157,7 +157,7 @@ public:
     // before calling them. This is not a trivial getter and its return value should be cached for
     // performance.
     size_t attributeCount() const;
-    const Attribute* attributeItem(unsigned index) const;
+    const Attribute& attributeItem(unsigned index) const;
     const Attribute* getAttributeItem(const QualifiedName&) const;
     size_t getAttributeItemIndex(const QualifiedName& name) const { return elementData()->getAttributeItemIndex(name); }
     size_t getAttributeItemIndex(const AtomicString& name, bool shouldIgnoreAttributeCase) const { return elementData()->getAttributeItemIndex(name, shouldIgnoreAttributeCase); }
@@ -767,7 +767,7 @@ inline size_t Element::attributeCount() const
     return elementData()->length();
 }
 
-inline const Attribute* Element::attributeItem(unsigned index) const
+inline const Attribute& Element::attributeItem(unsigned index) const
 {
     ASSERT(elementData());
     return elementData()->attributeItem(index);