Revert of Oilpan: Remove raw pointer to DescendantInvalidationSet from StyleInvalidator

Source/core/css/invalidation/StyleInvalidator.h

Index: Source/core/css/invalidation/StyleInvalidator.h
diff --git a/Source/core/css/invalidation/StyleInvalidator.h b/Source/core/css/invalidation/StyleInvalidator.h
index 23ba0143a3091bd5b494d28a90f44534a4ebcc84..440002260098e51a0748129c8d82599039d91aeb 100644
--- a/Source/core/css/invalidation/StyleInvalidator.h
+++ b/Source/core/css/invalidation/StyleInvalidator.h
@@ -29,9 +29,7 @@
     DECLARE_TRACE();
 
 private:
-    class RecursionData {
-        STACK_ALLOCATED();
-    public:
+    struct RecursionData {
         RecursionData()
             : m_invalidateCustomPseudo(false)
             , m_wholeSubtreeInvalid(false)
@@ -49,7 +47,7 @@
         bool treeBoundaryCrossing() const { return m_treeBoundaryCrossing; }
         bool insertionPointCrossing() const { return m_insertionPointCrossing; }
 
-        using InvalidationSets = WillBeHeapVector<RawPtrWillBeMember<const DescendantInvalidationSet>, 16>;
+        using InvalidationSets = Vector<const DescendantInvalidationSet*, 16>;
         InvalidationSets m_invalidationSets;
         bool m_invalidateCustomPseudo;
         bool m_wholeSubtreeInvalid;
@@ -62,7 +60,6 @@
     bool checkInvalidationSetsAgainstElement(Element&, RecursionData&);
 
     class RecursionCheckpoint {
-        STACK_ALLOCATED();
     public:
         RecursionCheckpoint(RecursionData* data)
             : m_prevInvalidationSetsSize(data->m_invalidationSets.size())
@@ -87,7 +84,6 @@
         bool m_prevWholeSubtreeInvalid;
         bool m_treeBoundaryCrossing;
         bool m_insertionPointCrossing;
-        // This is a stack reference and need not separate tracing.
         RecursionData* m_data;
     };