Utilize PassRefPtr and C++ refs in more places in ShadowRoot code

Source/core/html/HTMLTextAreaElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 82 matching lines @@
     ScriptWrappable::init(this);
 }
 
 PassRefPtr<HTMLTextAreaElement> HTMLTextAreaElement::create(const QualifiedName& tagName, Document& document, HTMLFormElement* form)
 {
     RefPtr<HTMLTextAreaElement> textArea = adoptRef(new HTMLTextAreaElement(tagName, document, form));
     textArea->ensureUserAgentShadowRoot();
     return textArea.release();
 }
 
-void HTMLTextAreaElement::didAddUserAgentShadowRoot(ShadowRoot* root)
+void HTMLTextAreaElement::didAddUserAgentShadowRoot(ShadowRoot& root)
 {
-    root->appendChild(TextControlInnerTextElement::create(document()));
+    root.appendChild(TextControlInnerTextElement::create(document()));
 }
 
 const AtomicString& HTMLTextAreaElement::formControlType() const
 {
     DEFINE_STATIC_LOCAL(const AtomicString, textarea, ("textarea", AtomicString::ConstructFromLiteral));
     return textarea;
 }
 
 FormControlState HTMLTextAreaElement::saveFormControlState() const
 {
@@ skipping 419 matching lines @@
     }
     placeholder->setTextContent(placeholderText, ASSERT_NO_EXCEPTION);
 }
 
 bool HTMLTextAreaElement::isInteractiveContent() const
 {
     return true;
 }
 
 }