Revert of Oilpan: Query stack frame register instead of manual bookkeeping

Source/platform/heap/Visitor.h

Index: Source/platform/heap/Visitor.h
diff --git a/Source/platform/heap/Visitor.h b/Source/platform/heap/Visitor.h
index da05ed36430dc711342b43f719fb60f3489f2509..b1de94998b1a039f4e9ce7b05625df5804539fbf 100644
--- a/Source/platform/heap/Visitor.h
+++ b/Source/platform/heap/Visitor.h
@@ -32,7 +32,6 @@
 #define Visitor_h
 
 #include "platform/PlatformExport.h"
-#include "platform/heap/StackFrameDepth.h"
 #include "platform/heap/ThreadState.h"
 #include "wtf/Assertions.h"
 #include "wtf/Deque.h"
@@ -613,25 +612,18 @@
     }
 #endif
 
-    inline bool canTraceEagerly() const
-    {
-        ASSERT(m_stackFrameDepth);
-        return m_stackFrameDepth->isSafeToRecurse();
-    }
-
-    inline void configureEagerTraceLimit()
-    {
-        if (!m_stackFrameDepth)
-            m_stackFrameDepth = new StackFrameDepth;
-        m_stackFrameDepth->configureLimit();
-    }
+    inline bool canTraceEagerly() const { return m_traceDepth < kMaxEagerTraceDepth; }
+    inline void incrementTraceDepth() { m_traceDepth++; }
+    inline void decrementTraceDepth() { ASSERT(m_traceDepth > 0); m_traceDepth--; }
 
     inline bool isGlobalMarkingVisitor() const { return m_isGlobalMarkingVisitor; }
 
 protected:
     explicit Visitor(VisitorType type)
         : m_isGlobalMarkingVisitor(type == GlobalMarkingVisitorType)
-    { }
+    {
+        m_traceDepth = 0;
+    }
 
     virtual void registerWeakCellWithCallback(void**, WeakPointerCallback) = 0;
 #if ENABLE(GC_PROFILE_MARKING)
@@ -646,8 +638,12 @@
 
 private:
     static Visitor* fromHelper(VisitorHelper<Visitor>* helper) { return static_cast<Visitor*>(helper); }
-    static StackFrameDepth* m_stackFrameDepth;
-
+
+    // The maximum depth of eager, unrolled trace() calls that is
+    // considered safe and allowed.
+    const int kMaxEagerTraceDepth = 100;
+
+    static int m_traceDepth;
     bool m_isGlobalMarkingVisitor;
 };
 
@@ -714,7 +710,9 @@
             ASSERT(visitor->canTraceEagerly());
             if (LIKELY(visitor->canTraceEagerly())) {
                 if (visitor->ensureMarked(t)) {
+                    visitor->incrementTraceDepth();
                     TraceTrait<T>::trace(visitor, const_cast<T*>(t));
+                    visitor->decrementTraceDepth();
                 }
                 return;
             }