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 59d7dfcf002f9229018a4965cdc0617eeef70541..0abdf9053b69f08141c6a17df7bbd38f2077222a 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -912,11 +912,19 @@ class Heap {
   const char* GetSpaceName(int idx);
 
   // ===========================================================================
-  // API. ======================================================================
+  // Embedder heap tracing. ====================================================
   // ===========================================================================
 
   void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
 
+  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
+
+  bool UsingEmbedderHeapTracer() {
+    return FLAG_trace_embedder_heap && embedder_heap_tracer_;
+  }
+
+  void TracePossibleWrapper(JSObject* js_object);
+
   void RegisterExternallyReferencedObject(Object** object);
 
   // ===========================================================================
@@ -927,8 +935,6 @@ 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();