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

Source/core/css/StyleRule.cpp

Index: Source/core/css/StyleRule.cpp
diff --git a/Source/core/css/StyleRule.cpp b/Source/core/css/StyleRule.cpp
index 70912141184e61da8eaa7a7eaca6ccc9129f8642..08e62bd74ac4ed34d3b4206d2156079a5579ceb6 100644
--- a/Source/core/css/StyleRule.cpp
+++ b/Source/core/css/StyleRule.cpp
@@ -363,7 +363,7 @@ void StyleRuleGroup::traceAfterDispatch(Visitor* visitor)
     StyleRuleBase::traceAfterDispatch(visitor);
 }
 
-StyleRuleMedia::StyleRuleMedia(PassRefPtr<MediaQuerySet> media, WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase> >& adoptRules)
+StyleRuleMedia::StyleRuleMedia(PassRefPtrWillBeRawPtr<MediaQuerySet> media, WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase> >& adoptRules)
     : StyleRuleGroup(Media, adoptRules)
     , m_mediaQueries(media)
 {
@@ -376,6 +376,12 @@ StyleRuleMedia::StyleRuleMedia(const StyleRuleMedia& o)
         m_mediaQueries = o.m_mediaQueries->copy();
 }
 
+void StyleRuleMedia::traceAfterDispatch(Visitor* visitor)
+{
+    visitor->trace(m_mediaQueries);
+    StyleRuleGroup::traceAfterDispatch(visitor);
+}
+
 StyleRuleSupports::StyleRuleSupports(const String& conditionText, bool conditionIsSupported, WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase> >& adoptRules)
     : StyleRuleGroup(Supports, adoptRules)
     , m_conditionText(conditionText)