Implement a Hit Test Cache.

Source/core/layout/line/RootInlineBox.cpp

 /*
  * Copyright (C) 2003, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 141 matching lines @@
 
 void RootInlineBox::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset, LayoutUnit lineTop, LayoutUnit lineBottom)
 {
     RootInlineBoxPainter(*this).paint(paintInfo, paintOffset, lineTop, lineBottom);
 }
 
 bool RootInlineBox::nodeAtPoint(HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, LayoutUnit lineTop, LayoutUnit lineBottom)
 {
     if (hasEllipsisBox() && visibleToHitTestRequest(result.hitTestRequest())) {
         if (ellipsisBox()->nodeAtPoint(result, locationInContainer, accumulatedOffset, lineTop, lineBottom)) {
-            layoutObject().updateHitTestResult(result, locationInContainer.point() - toLayoutSize(accumulatedOffset));
+            // TODO(dtapuska): Calculate the right line box
+            layoutObject().updateHitTestResult(result, locationInContainer.point() - toLayoutSize(accumulatedOffset), result.validityRect());
             return true;
         }
     }
     return InlineFlowBox::nodeAtPoint(result, locationInContainer, accumulatedOffset, lineTop, lineBottom);
 }
 
 void RootInlineBox::adjustPosition(FloatWillBeLayoutUnit dx, FloatWillBeLayoutUnit dy)
 {
     InlineFlowBox::adjustPosition(dx, dy);
     LayoutUnit blockDirectionDelta = isHorizontal() ? dy : dx; // The block direction delta is a LayoutUnit.
@@ skipping 674 matching lines @@
     endBox = 0;
     return 0;
 }
 
 const char* RootInlineBox::boxName() const
 {
     return "RootInlineBox";
 }
 
 } // namespace blink