Have Attr constructor take a Document / Element reference

Source/core/dom/Attr.h

Index: Source/core/dom/Attr.h
diff --git a/Source/core/dom/Attr.h b/Source/core/dom/Attr.h
index 21b36857fd156c5afa7b561ae2e11502302995fe..bd9e7eb5e2ee26fa3ab24218a5536cf3a708fed3 100644
--- a/Source/core/dom/Attr.h
+++ b/Source/core/dom/Attr.h
@@ -42,8 +42,8 @@ class MutableStylePropertySet;
 
 class Attr FINAL : public ContainerNode {
 public:
-    static PassRefPtr<Attr> create(Element*, const QualifiedName&);
-    static PassRefPtr<Attr> create(Document*, const QualifiedName&, const AtomicString& value);
+    static PassRefPtr<Attr> create(Element&, const QualifiedName&);
+    static PassRefPtr<Attr> create(Document&, const QualifiedName&, const AtomicString& value);
     virtual ~Attr();
 
     String name() const { return qualifiedName().toString(); }
@@ -70,8 +70,8 @@ public:
     virtual void setPrefix(const AtomicString&, ExceptionState&) OVERRIDE;
 
 private:
-    Attr(Element*, const QualifiedName&);
-    Attr(Document*, const QualifiedName&, const AtomicString& value);
+    Attr(Element&, const QualifiedName&);
+    Attr(Document&, const QualifiedName&, const AtomicString& value);
 
     void createTextChild();