[cleanup] Remove unused heap_iterator_depth counter

Bug: v8:8834
Change-Id: I763869297e52baf1142f89f0567441c05e00391c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1552784Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Cr-Commit-Position: refs/heads/master@{#60633}

src/heap/heap.cc

@@ -5352,7 +5352,6 @@ HeapIterator::HeapIterator(Heap* heap,
       space_iterator_(nullptr),
       object_iterator_(nullptr) {
   heap_->MakeHeapIterable();
-  heap_->heap_iterator_start();
   // Start the iteration.
   space_iterator_ = new SpaceIterator(heap_);
   switch (filtering_) {
@@ -5367,7 +5366,6 @@ HeapIterator::HeapIterator(Heap* heap,
 
 
 HeapIterator::~HeapIterator() {
-  heap_->heap_iterator_end();
 #ifdef DEBUG
   // Assert that in filtering mode we have iterated through all
   // objects. Otherwise, heap will be left in an inconsistent state.

src/heap/heap.h

@@ -1694,16 +1694,6 @@ class Heap {
   bool RecentIdleNotificationHappened();
   void ScheduleIdleScavengeIfNeeded(int bytes_allocated);
 
-  // ===========================================================================
-  // HeapIterator helpers. =====================================================
-  // ===========================================================================
-
-  void heap_iterator_start() { heap_iterator_depth_++; }
-
-  void heap_iterator_end() { heap_iterator_depth_--; }
-
-  bool in_heap_iterator() { return heap_iterator_depth_ > 0; }
-
   // ===========================================================================
   // Allocation methods. =======================================================
   // ===========================================================================
@@ -2011,9 +2001,6 @@ class Heap {
 
   bool deserialization_complete_ = false;
 
-  // The depth of HeapIterator nestings.
-  int heap_iterator_depth_ = 0;
-
   bool fast_promotion_mode_ = false;
 
   // Used for testing purposes.