Revert of "[heap] Fine-grained JSArrayBuffer tracking"

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index a4d36b8c5c1225329ab1ea020de9a139ec7d1998..cbf62bdb2d339166c2c293cb9267c8a560d6d3e0 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -511,14 +511,13 @@
   chunk->progress_bar_ = 0;
   chunk->high_water_mark_.SetValue(static_cast<intptr_t>(area_start - base));
   chunk->concurrent_sweeping_state().SetValue(kSweepingDone);
-  chunk->mutex_ = new base::Mutex();
+  chunk->mutex_ = nullptr;
   chunk->available_in_free_list_ = 0;
   chunk->wasted_memory_ = 0;
   chunk->ResetLiveBytes();
   Bitmap::Clear(chunk);
   chunk->set_next_chunk(nullptr);
   chunk->set_prev_chunk(nullptr);
-  chunk->local_tracker_ = nullptr;
 
   DCHECK(OFFSET_OF(MemoryChunk, flags_) == kFlagsOffset);
   DCHECK(OFFSET_OF(MemoryChunk, live_byte_count_) == kLiveBytesOffset);
@@ -1040,8 +1039,6 @@
   if (old_to_old_slots_ != nullptr) ReleaseOldToOldSlots();
   if (typed_old_to_new_slots_ != nullptr) ReleaseTypedOldToNewSlots();
   if (typed_old_to_old_slots_ != nullptr) ReleaseTypedOldToOldSlots();
-
-  if (local_tracker_ != nullptr) ReleaseLocalTracker();
 }
 
 static SlotSet* AllocateSlotSet(size_t size, Address page_start) {
@@ -1093,12 +1090,6 @@
   delete typed_old_to_old_slots_;
   typed_old_to_old_slots_ = nullptr;
 }
-
-void MemoryChunk::ReleaseLocalTracker() {
-  delete local_tracker_;
-  local_tracker_ = nullptr;
-}
-
 // -----------------------------------------------------------------------------
 // PagedSpace implementation