Replace raw pointers to GC allocated objects by members in stack allocated objects.

Source/core/css/CSSValueList.h

Index: Source/core/css/CSSValueList.h
diff --git a/Source/core/css/CSSValueList.h b/Source/core/css/CSSValueList.h
index 7e4d9ff600eb70a2aa03a8085860e0f19747e209..310f16b9f570d91fd4b945d0de0f3b3658e52cbf 100644
--- a/Source/core/css/CSSValueList.h
+++ b/Source/core/css/CSSValueList.h
@@ -93,7 +93,7 @@ public:
     CSSValue* second() const { return item(1); }
     size_t length() const { return m_list ? m_list->length() : 0; }
 private:
-    CSSValueList* m_list;
+    RawPtrWillBeMember<CSSValueList> m_list;
 };
 
 // Wrapper that can be used to iterate over any CSSValue. Non-list values and 0 behave as zero-length lists.