Fixed perf regression by removing tree traversal for text sibling.

third_party/WebKit/Source/core/dom/Node.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004-2011, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 180 matching lines @@
   ContainerNode* parentNode() const;
   Element* parentElement() const;
   ContainerNode* parentElementOrShadowRoot() const;
   ContainerNode* parentElementOrDocumentFragment() const;
   Node* previousSibling() const { return m_previous; }
   Node* nextSibling() const { return m_next; }
   NodeList* childNodes();
   Node* firstChild() const;
   Node* lastChild() const;
   Node* getRootNode(const GetRootNodeOptions&) const;
-  Text* nextTextSibling() const;
   Node& treeRoot() const;
   Node& shadowIncludingRoot() const;
   // closed-shadow-hidden is defined at
   // https://dom.spec.whatwg.org/#concept-closed-shadow-hidden
   bool isClosedShadowHiddenFrom(const Node&) const;
 
   void prepend(const HeapVector<NodeOrString>&, ExceptionState&);
   void append(const HeapVector<NodeOrString>&, ExceptionState&);
   void before(const HeapVector<NodeOrString>&, ExceptionState&);
   void after(const HeapVector<NodeOrString>&, ExceptionState&);
@@ skipping 801 matching lines @@
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showNode(const blink::Node*);
 void showTree(const blink::Node*);
 void showNodePath(const blink::Node*);
 #endif
 
 #endif  // Node_h