Change various helper classes to transition types to get CSSValue entirely onto the gc heap.

Source/core/css/StyleRule.h

Index: Source/core/css/StyleRule.h
diff --git a/Source/core/css/StyleRule.h b/Source/core/css/StyleRule.h
index a55cb5c8e888a8d61b3436b2cdbf4d703847e3ab..f668d9130cc8cf0a41e4b642c5093512b5f67738 100644
--- a/Source/core/css/StyleRule.h
+++ b/Source/core/css/StyleRule.h
@@ -195,7 +195,7 @@ private:
 
 class StyleRuleMedia : public StyleRuleGroup {
 public:
-    static PassRefPtrWillBeRawPtr<StyleRuleMedia> create(PassRefPtr<MediaQuerySet> media, Vector<RefPtr<StyleRuleBase> >& adoptRules)
+    static PassRefPtrWillBeRawPtr<StyleRuleMedia> create(PassRefPtrWillBeRawPtr<MediaQuerySet> media, Vector<RefPtr<StyleRuleBase> >& adoptRules)
     {
         return adoptRefCountedWillBeRefCountedGarbageCollected(new StyleRuleMedia(media, adoptRules));
     }
@@ -207,10 +207,10 @@ public:
     void traceAfterDispatch(Visitor* visitor) { StyleRuleGroup::traceAfterDispatch(visitor); }
 
 private:
-    StyleRuleMedia(PassRefPtr<MediaQuerySet>, Vector<RefPtr<StyleRuleBase> >& adoptRules);
+    StyleRuleMedia(PassRefPtrWillBeRawPtr<MediaQuerySet>, Vector<RefPtr<StyleRuleBase> >& adoptRules);
     StyleRuleMedia(const StyleRuleMedia&);
 
-    RefPtr<MediaQuerySet> m_mediaQueries;
+    RefPtrWillBePersistent<MediaQuerySet> m_mediaQueries;
 };
 
 class StyleRuleSupports : public StyleRuleGroup {