Remove now-unused Visitor::m_isGlobalMarkingVisitor field.

third_party/WebKit/Source/platform/heap/Visitor.h

 /*
  * 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 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef Visitor_h
 #define Visitor_h
 
 #include "platform/PlatformExport.h"
 #include "platform/heap/GarbageCollected.h"
-#include "platform/heap/StackFrameDepth.h"
-#include "platform/heap/ThreadState.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
-#include "wtf/Atomics.h"
 #include "wtf/Deque.h"
 #include "wtf/Forward.h"
-#include "wtf/HashMap.h"
 #include "wtf/HashTraits.h"
 #include "wtf/TypeTraits.h"
 
 namespace blink {
 
 template<typename T> class GarbageCollected;
 class HeapObjectHeader;
 class InlinedGlobalMarkingVisitor;
 template<typename T> class TraceTrait;
 template<typename T> class TraceEagerlyTrait;
@@ skipping 324 matching lines @@
 protected:
     Visitor(ThreadState*, MarkingMode);
 
     virtual void registerWeakCellWithCallback(void**, WeakCallback) = 0;
 
 private:
     static Visitor* fromHelper(VisitorHelper<Visitor>* helper) { return static_cast<Visitor*>(helper); }
 
     ThreadState* m_state;
     const MarkingMode m_markingMode;
-    bool m_isGlobalMarkingVisitor;

[haraken, 2016/03/04 15:55:59]

Hmm, I remember kouhei@ introduced this flag for optimizing the marking phase.
Would you quickly blame a CL that removes the usage of m_isGlobalMarkingVisitor?

[sof, 2016/03/04 18:18:23]

Yes, introduced in https://codereview.chromium.org/804303002 and no longer used
after https://codereview.chromium.org/1168683002

 };
 
 } // namespace blink
 
 #endif // Visitor_h