Introduce Node::containingTreeScope(), which asserts that the node's root is a tree scope

third_party/WebKit/Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * 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 218 matching lines @@
         return frame->deprecatedLocalOwner();
     return nullptr;
 }
 
 ScopedFocusNavigation ScopedFocusNavigation::createFor(const Element& current)
 {
     if (HTMLSlotElement* slot = SlotScopedTraversal::findScopeOwnerSlot(current))
         return ScopedFocusNavigation(*slot, &current);
     if (HTMLSlotElement* slot = ScopedFocusNavigation::findFallbackScopeOwnerSlot(current))
         return ScopedFocusNavigation(*slot, &current);
-    return ScopedFocusNavigation(current.treeScope(), &current);
+    return ScopedFocusNavigation(current.containingTreeScope(), &current);
 }
 
 ScopedFocusNavigation ScopedFocusNavigation::createForDocument(Document& document)
 {
     return ScopedFocusNavigation(document, nullptr);
 }
 
 ScopedFocusNavigation ScopedFocusNavigation::ownedByNonFocusableFocusScopeOwner(Element& element)
 {
     if (isShadowHost(element))
@@ skipping 1058 matching lines @@
     return consumed;
 }
 
 DEFINE_TRACE(FocusController)
 {
     visitor->trace(m_page);
     visitor->trace(m_focusedFrame);
 }
 
 } // namespace blink