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

Source/core/css/MediaQueryMatcher.cpp

Index: Source/core/css/MediaQueryMatcher.cpp
diff --git a/Source/core/css/MediaQueryMatcher.cpp b/Source/core/css/MediaQueryMatcher.cpp
index 3f156a375a97903e0cbaeb1751ff51441a777914..8f115197bbcee6494fa3450538d1727243c49361 100644
--- a/Source/core/css/MediaQueryMatcher.cpp
+++ b/Source/core/css/MediaQueryMatcher.cpp
@@ -103,7 +103,7 @@ PassRefPtr<MediaQueryList> MediaQueryMatcher::matchMedia(const String& query)
     if (!m_document)
         return nullptr;
 
-    RefPtr<MediaQuerySet> media = MediaQuerySet::create(query);
+    RefPtrWillBeRawPtr<MediaQuerySet> media = MediaQuerySet::create(query);
     // Add warning message to inspector whenever dpi/dpcm values are used for "screen" media.
     reportMediaQueryWarningIfNeeded(m_document, media.get());
     return MediaQueryList::create(this, media, evaluate(media.get()));