ASSERT that Visitor::mark is only called when inGC()

Source/platform/heap/Heap.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1833 matching lines @@
     friend class MarkingVisitorImpl<MarkingVisitor<Mode>>;
 
 #if ENABLE(GC_PROFILE_MARKING)
     using LiveObjectSet = HashSet<uintptr_t>;
     using LiveObjectMap = HashMap<String, LiveObjectSet>;
     using ObjectGraph = HashMap<uintptr_t, std::pair<uintptr_t, String>>;
 #endif
 
     MarkingVisitor()
         : Visitor(Mode == GlobalMarking ? Visitor::GlobalMarkingVisitorType : Visitor::GenericVisitorType)
+#if ENABLE(ASSERT)
+        , m_allowMarkingForHashTableWeakProcessing(false)
+#endif
     {
     }
 
     virtual void markHeader(HeapObjectHeader* header, TraceCallback callback) override
     {
         Impl::visitHeader(header, header->payload(), callback);
     }
 
     virtual void mark(const void* objectPointer, TraceCallback callback) override
     {
@@ skipping 152 matching lines @@
         if (Mode != ThreadLocalMarking)
             return true;
 
         BaseHeapPage* page = pageFromObject(objectPointer);
         ASSERT(!page->orphaned());
         // When doing a thread local GC, the marker checks if
         // the object resides in another thread's heap. If it
         // does, the object should not be marked & traced.
         return page->terminating();
     }
+
+#if ENABLE(ASSERT)
+    virtual void checkMarkingAllowed() override
+    {
+        ASSERT(ThreadState::current()->isInGC() || m_allowMarkingForHashTableWeakProcessing);
+    }
+
+    virtual void setAllowMarkingForHashTableWeakProcessing(bool allow) override
+    {
+        m_allowMarkingForHashTableWeakProcessing = allow;
+    }
+
+    bool m_allowMarkingForHashTableWeakProcessing;
+#endif
 };
 
 void Heap::init()
 {
     ThreadState::init();
     s_markingStack = new CallbackStack();
     s_postMarkingCallbackStack = new CallbackStack();
     s_weakCallbackStack = new CallbackStack();
     s_ephemeronStack = new CallbackStack();
     s_heapDoesNotContainCache = new HeapDoesNotContainCache();
@@ skipping 650 matching lines @@
 bool Heap::s_shutdownCalled = false;
 bool Heap::s_lastGCWasConservative = false;
 FreePagePool* Heap::s_freePagePool;
 OrphanedPagePool* Heap::s_orphanedPagePool;
 Heap::RegionTree* Heap::s_regionTree = nullptr;
 size_t Heap::s_allocatedObjectSize = 0;
 size_t Heap::s_allocatedSpace = 0;
 size_t Heap::s_markedObjectSize = 0;
 
 } // namespace blink