Move CSSRuleList to the garbage collected heap

Source/core/css/StyleSheetList.cpp

Index: Source/core/css/StyleSheetList.cpp
diff --git a/Source/core/css/StyleSheetList.cpp b/Source/core/css/StyleSheetList.cpp
index bc6b0df930638eda87328d74902cea1a6434bbfd..f5dc2200cdef4ac4ffc173ebf410235de3a8e208 100644
--- a/Source/core/css/StyleSheetList.cpp
+++ b/Source/core/css/StyleSheetList.cpp
@@ -40,7 +40,7 @@ StyleSheetList::~StyleSheetList()
 {
 }
 
-inline const Vector<RefPtr<StyleSheet> >& StyleSheetList::styleSheets()
+inline const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& StyleSheetList::styleSheets()
 {
     if (!m_treeScope)
         return m_detachedStyleSheets;
@@ -60,7 +60,7 @@ unsigned StyleSheetList::length()
 
 StyleSheet* StyleSheetList::item(unsigned index)
 {
-    const Vector<RefPtr<StyleSheet> >& sheets = styleSheets();
+    const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& sheets = styleSheets();
     return index < sheets.size() ? sheets[index].get() : 0;
 }
 
@@ -91,6 +91,7 @@ CSSStyleSheet* StyleSheetList::anonymousNamedGetter(const AtomicString& name)
 
 void StyleSheetList::trace(Visitor* visitor)
 {
+    m_detachedStyleSheets.trace(visitor);
 }
 
 } // namespace WebCore