Make all references from root shortcuts (except one to GC roots)

src/heap-snapshot-generator.cc

Index: src/heap-snapshot-generator.cc
diff --git a/src/heap-snapshot-generator.cc b/src/heap-snapshot-generator.cc
index 680e1cc4ad74b748aca7952dc30672973a2eae08..6b93f71ac3f810efcc53644d0d281c665d617041 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -2517,10 +2517,8 @@ void NativeObjectsExplorer::SetRootNativeRootsReference() {
     HeapEntry* group_entry =
         filler_->FindOrAddEntry(group_info, native_entries_allocator_);
     DCHECK(group_entry != NULL);
-    filler_->SetIndexedAutoIndexReference(
-        HeapGraphEdge::kElement,
-        snapshot_->root()->index(),
-        group_entry);
+    filler_->SetNamedAutoIndexReference(
+        HeapGraphEdge::kShortcut, snapshot_->root()->index(), group_entry);
   }
 }