[heap] Prevent leakage of GCCallbacksScope outside of heap.

src/heap/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 740 matching lines @@
     : heap_(isolate->heap()) {
   heap_->always_allocate_scope_count_.Increment(1);
 }
 
 
 AlwaysAllocateScope::~AlwaysAllocateScope() {
   heap_->always_allocate_scope_count_.Increment(-1);
 }
 
 
-GCCallbacksScope::GCCallbacksScope(Heap* heap) : heap_(heap) {
-  heap_->gc_callbacks_depth_++;
-}
-
-
-GCCallbacksScope::~GCCallbacksScope() { heap_->gc_callbacks_depth_--; }
-
-
-bool GCCallbacksScope::CheckReenter() {
-  return heap_->gc_callbacks_depth_ == 1;
-}
-
-
 void VerifyPointersVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     if ((*current)->IsHeapObject()) {
       HeapObject* object = HeapObject::cast(*current);
       CHECK(object->GetIsolate()->heap()->Contains(object));
       CHECK(object->map()->IsMap());
     }
   }
 }
 
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_INL_H_