Bounding boxes in the accessibility tree should always be relative to a box.

third_party/WebKit/Source/modules/accessibility/AXObject.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 1509 matching lines @@
   }
 
   // First compute the container. The container must be an ancestor in the
   // accessibility tree, and its LayoutObject must be an ancestor in the layout
   // tree. Get the first such ancestor that's either scrollable or has a paint
   // layer.
   AXObject* container = ParentObjectUnignored();
   LayoutObject* container_layout_object = nullptr;
   while (container) {
     container_layout_object = container->GetLayoutObject();
-    if (container_layout_object &&
-        container_layout_object->IsBoxModelObject() &&
+    if (container_layout_object && container_layout_object->IsBox() &&
         layout_object->IsDescendantOf(container_layout_object)) {
       if (container->IsScrollableContainer() ||
           container_layout_object->HasLayer())
         break;
     }
 
     container = container->ParentObjectUnignored();
   }
 
   if (!container)
@@ skipping 558 matching lines @@
 }
 
 DEFINE_TRACE(AXObject) {
   visitor->Trace(children_);
   visitor->Trace(parent_);
   visitor->Trace(cached_live_region_root_);
   visitor->Trace(ax_object_cache_);
 }
 
 }  // namespace blink