[heap] Prevent leakage of GCCallbacksScope outside of heap.

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index dbb3e95866f9426fed6e213ad9df7c8a855bcb5f..8781685ad4838ce76dc4389fb325b3bc6055da67 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -758,19 +758,6 @@ AlwaysAllocateScope::~AlwaysAllocateScope() {
 }
 
 
-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()) {