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

Source/web/LinkHighlight.h

 /*
  * 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:
  *
  * 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 57 matching lines @@
     virtual void invalidate() override;
     virtual WebLayer* layer() override;
     virtual void clearCurrentGraphicsLayer() override;
 
     GraphicsLayer* currentGraphicsLayerForTesting() const { return m_currentGraphicsLayer; }
 
 private:
     LinkHighlight(Node*, WebViewImpl*);
 
     void releaseResources();
-    void computeQuads(RenderObject&, WTF::Vector<FloatQuad>&) const;
+    void computeQuads(const Node&, WTF::Vector<FloatQuad>&) const;
 
     RenderLayer* computeEnclosingCompositingLayer();
     void clearGraphicsLayerLinkHighlightPointer();
     // This function computes the highlight path, and returns true if it has changed
     // size since the last call to this function.
     bool computeHighlightLayerPathAndPosition(RenderLayer*);
 
     OwnPtr<WebContentLayer> m_contentLayer;
     OwnPtr<WebLayer> m_clipLayer;
     Path m_path;
     RefPtr<DisplayList> m_displayList;
 
     RefPtrWillBePersistent<Node> m_node;
     WebViewImpl* m_owningWebViewImpl;
     GraphicsLayer* m_currentGraphicsLayer;
 
     bool m_geometryNeedsUpdate;
     bool m_isAnimating;
     double m_startTime;
 };
 
 } // namespace blink
 
 #endif