Use EmbedderHeapTracer instead of object grouping when trace_embedder_heap flag is set

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index ab121873ed1606a54eddb512c7478e558713152c..b7ec5c3546f6a3cf1583b65dd24e1edfd93e208a 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -725,6 +725,14 @@ class Heap {
   // Returns false if not able to reserve.
   bool ReserveSpace(Reservation* reservations);
 
+  void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
+
+  bool UsingEmbedderHeapTracer();
+
+  void TracePossibleWrapper(JSObject* js_object);
+
+  void RegisterExternallyReferencedObject(Object** object);
+
   //
   // Support for the API.
   //
@@ -911,14 +919,6 @@ class Heap {
   const char* GetSpaceName(int idx);
 
   // ===========================================================================
-  // API. ======================================================================
-  // ===========================================================================
-
-  void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
-
-  void RegisterExternallyReferencedObject(Object** object);
-
-  // ===========================================================================
   // Getters to other components. ==============================================
   // ===========================================================================
 
@@ -926,8 +926,6 @@ class Heap {
 
   MemoryAllocator* memory_allocator() { return memory_allocator_; }
 
-  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
-
   PromotionQueue* promotion_queue() { return &promotion_queue_; }
 
   inline Isolate* isolate();
@@ -2099,7 +2097,6 @@ class Heap {
   int deferred_counters_[v8::Isolate::kUseCounterFeatureCount];
 
   GCTracer* tracer_;
-  EmbedderHeapTracer* embedder_heap_tracer_;
 
   int high_survival_rate_period_length_;
   intptr_t promoted_objects_size_;