[Oilpan]: Make StylePropertySet fully garbage collected.

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 3118 matching lines @@
 CSSStyleDeclaration* Element::style()
 {
     if (!isStyledElement())
         return 0;
     return &ensureElementRareData().ensureInlineCSSStyleDeclaration(this);
 }
 
 MutableStylePropertySet& Element::ensureMutableInlineStyle()
 {
     ASSERT(isStyledElement());
-    RefPtr<StylePropertySet>& inlineStyle = ensureUniqueElementData().m_inlineStyle;
+    RefPtrWillBeMember<StylePropertySet>& inlineStyle = ensureUniqueElementData().m_inlineStyle;
     if (!inlineStyle) {
         CSSParserMode mode = (!isHTMLElement() || document().inQuirksMode()) ? HTMLQuirksMode : HTMLStandardMode;
         inlineStyle = MutableStylePropertySet::create(mode);
     } else if (!inlineStyle->isMutable()) {
         inlineStyle = inlineStyle->mutableCopy();
     }
     return *toMutableStylePropertySet(inlineStyle);
 }
 
 void Element::clearMutableInlineStyleIfEmpty()
 {
     if (ensureMutableInlineStyle().isEmpty()) {
         ensureUniqueElementData().m_inlineStyle.clear();
     }
 }
 
 inline void Element::setInlineStyleFromString(const AtomicString& newStyleString)
 {
     ASSERT(isStyledElement());
-    RefPtr<StylePropertySet>& inlineStyle = elementData()->m_inlineStyle;
+    RefPtrWillBeMember<StylePropertySet>& inlineStyle = elementData()->m_inlineStyle;
 
     // Avoid redundant work if we're using shared attribute data with already parsed inline style.
     if (inlineStyle && !elementData()->isUnique())
         return;
 
     // We reconstruct the property set instead of mutating if there is no CSSOM wrapper.
     // This makes wrapperless property sets immutable and so cacheable.
     if (inlineStyle && !inlineStyle->isMutable())
         inlineStyle.clear();
 
     if (!inlineStyle) {
         inlineStyle = BisonCSSParser::parseInlineStyleDeclaration(newStyleString, this);
     } else {
         ASSERT(inlineStyle->isMutable());
-        static_pointer_cast<MutableStylePropertySet>(inlineStyle)->parseDeclaration(newStyleString, document().elementSheet().contents());
+        static_cast<MutableStylePropertySet*>(inlineStyle.get())->parseDeclaration(newStyleString, document().elementSheet().contents());
     }
 }
 
 void Element::styleAttributeChanged(const AtomicString& newStyleString, AttributeModificationReason modificationReason)
 {
     ASSERT(isStyledElement());
     WTF::OrdinalNumber startLineNumber = WTF::OrdinalNumber::beforeFirst();
     if (document().scriptableDocumentParser() && !document().isInDocumentWrite())
         startLineNumber = document().scriptableDocumentParser()->lineNumber();
 
@@ skipping 134 matching lines @@
         return false;
     if (FullscreenElementStack::isActiveFullScreenElement(*this))
         return false;
     return true;
 }
 
 void Element::trace(Visitor* visitor)
 {
     if (hasRareData())
         visitor->trace(elementRareData());
-
+    visitor->trace(m_elementData);
     ContainerNode::trace(visitor);
 }
 
 } // namespace WebCore