Implement Visitor::isGlobalMarkingVisitor

Source/platform/heap/HeapTest.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 217 matching lines @@
     }                                                                      \
     virtual bool isMarked(const Type*) override { return false; }          \
     virtual bool ensureMarked(const Type* objectPointer) override          \
     {                                                                      \
         return ensureMarked(objectPointer);                                \
     }
 
 class CountingVisitor : public Visitor {
 public:
     CountingVisitor()
-        : m_count(0)
+        : Visitor(Visitor::GenericVisitorType)
+        , m_count(0)
     {
     }
 
     virtual void mark(const void* object, TraceCallback) override
     {
         if (object)
             m_count++;
     }
 
     virtual void mark(HeapObjectHeader* header, TraceCallback callback) override
@@ skipping 5091 matching lines @@
     Heap::collectGarbage(ThreadState::NoHeapPointersOnStack);
 
     // Verify that the DeepEagerly chain isn't completely unravelled
     // by performing eager trace() calls, but the explicit mark
     // stack is switched once some nesting limit is exceeded.
     EXPECT_GT(DeepEagerly::sTraceLazy, 2);
 #endif
 }
 
 } // namespace blink