Get rid of TreeBoundaryCrossingRules.

Source/core/dom/TreeScope.h

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 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 123 matching lines @@
     TreeScope* commonAncestorTreeScope(TreeScope& other);
 
     Element* getElementByAccessKey(const String& key) const;
 
     DECLARE_VIRTUAL_TRACE();
 
     ScopedStyleResolver* scopedStyleResolver() const { return m_scopedStyleResolver.get(); }
     ScopedStyleResolver& ensureScopedStyleResolver();
     void clearScopedStyleResolver();
 
+    TreeScope* composedParent();
+
+    static TreeScope* treeScopeInComposedTree(const Node&);
+
 protected:
     TreeScope(ContainerNode&, Document&);
     TreeScope(Document&);
     virtual ~TreeScope();
 
 #if !ENABLE(OILPAN)
     void destroyTreeScopeData();
 #endif
 
     void setDocument(Document& document) { m_document = &document; }
     void setParentTreeScope(TreeScope&);
+    void clearComposedParent() { m_composedParent = nullptr; }
 
 #if !ENABLE(OILPAN)
     bool hasGuardRefCount() const { return m_guardRefCount; }
 #endif
 
     void setNeedsStyleRecalcForViewportUnits();
 
 private:
 #if !ENABLE(OILPAN)
     virtual void dispose() { }
 
     int refCount() const;
 
 #if ENABLE(SECURITY_ASSERT)
     bool deletionHasBegun();
     void beginDeletion();
 #else
     bool deletionHasBegun() { return false; }
     void beginDeletion() { }
 #endif
 #endif
 
     bool rootNodeHasTreeSharedParent() const;
 
     RawPtrWillBeMember<ContainerNode> m_rootNode;
     RawPtrWillBeMember<Document> m_document;
     RawPtrWillBeMember<TreeScope> m_parentTreeScope;
+    RawPtrWillBeMember<TreeScope> m_composedParent;
 
 #if !ENABLE(OILPAN)
     int m_guardRefCount;
 #endif
 
     OwnPtrWillBeMember<DocumentOrderedMap> m_elementsById;
     OwnPtrWillBeMember<DocumentOrderedMap> m_imageMapsByName;
     OwnPtrWillBeMember<DocumentOrderedMap> m_labelsByForAttribute;
 
     OwnPtrWillBeMember<IdTargetObserverRegistry> m_idTargetObserverRegistry;
@@ skipping 14 matching lines @@
     return m_elementsById && m_elementsById->containsMultiple(id);
 }
 
 DEFINE_COMPARISON_OPERATORS_WITH_REFERENCES(TreeScope)
 
 HitTestResult hitTestInDocument(const Document*, int x, int y);
 
 } // namespace blink
 
 #endif // TreeScope_h