Use a composed tree based traversal in computing quads in LinkHighlight::computeQuads().

Source/core/dom/NodeRenderingTraversal.cpp

 /*
  * Copyright (C) 2012 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 145 matching lines @@
         return 0;
 
     if (Node* previousNode = pseudoAwarePreviousSibling(node)) {
         while (Node* previousLastChild = pseudoAwareLastChild(previousNode))
             previousNode = previousLastChild;
         return previousNode;
     }
     return parent(node);
 }
 
-static Node* firstChild(const Node* node)
+Node* firstChild(const Node* node)
 {
     ComposedTreeWalker walker(node);
     walker.firstChild();
     return walker.get();
 }
 
 static Node* pseudoAwareNextSibling(const Node* node)
 {
     Node* parentNode = parent(node);
     Node* nextNode = nextSibling(node);
@@ skipping 72 matching lines @@
     for (size_t i = position + 1; i < topLayerElements.size(); ++i) {
         if (RenderObject* renderer = topLayerElements[i]->renderer())
             return renderer;
     }
     return 0;
 }
 
 }
 
 } // namespace