Negative or zero radius for <area shape=circle> gives an empty shape

third_party/WebKit/Source/core/html/HTMLAreaElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2009, 2011 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.
  *
@@ skipping 142 matching lines @@
         if (m_coords.size() >= 6) {
             int numPoints = m_coords.size() / 2;
             path.moveTo(FloatPoint(clampCoordinate(m_coords[0]), clampCoordinate(m_coords[1])));
             for (int i = 1; i < numPoints; ++i)
                 path.addLineTo(FloatPoint(clampCoordinate(m_coords[i * 2]), clampCoordinate(m_coords[i * 2 + 1])));
             path.closeSubpath();
             path.setWindRule(RULE_EVENODD);
         }
         break;
     case Circle:
-        if (m_coords.size() >= 3) {
+        if (m_coords.size() >= 3 && m_coords[2].value() > 0) {
             float r = clampCoordinate(m_coords[2]);
             path.addEllipse(FloatRect(clampCoordinate(m_coords[0]) - r, clampCoordinate(m_coords[1]) - r, 2 * r, 2 * r));
         }
         break;
     case Rect:
         if (m_coords.size() >= 4) {
             float x0 = clampCoordinate(m_coords[0]);
             float y0 = clampCoordinate(m_coords[1]);
             float x1 = clampCoordinate(m_coords[2]);
             float y1 = clampCoordinate(m_coords[3]);
@@ skipping 57 matching lines @@
 void HTMLAreaElement::updateFocusAppearance(SelectionBehaviorOnFocus selectionBehavior)
 {
     if (!isFocusable())
         return;
 
     if (HTMLImageElement* imageElement = this->imageElement())
         imageElement->updateFocusAppearance(selectionBehavior);
 }
 
 } // namespace blink