Fix getBBox() returning (0,0) bug when width or height is zero

Source/core/rendering/svg/RenderSVGRect.cpp

 /*
  * Copyright (C) 2011 University of Szeged
  * Copyright (C) 2011 Renata Hodovan <reni@webkit.org>
  * 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.
@@ skipping 45 matching lines @@
     SVGLengthContext lengthContext(rect);
     // Fallback to RenderSVGShape if rect has rounded corners or a non-scaling stroke.
     if (rect->rx()->currentValue()->value(lengthContext) > 0 || rect->ry()->currentValue()->value(lengthContext) > 0 || hasNonScalingStroke()) {
         RenderSVGShape::updateShapeFromElement();
         m_usePathFallback = true;
         return;
     }
 
     m_usePathFallback = false;
     FloatSize boundingBoxSize(rect->width()->currentValue()->value(lengthContext), rect->height()->currentValue()->value(lengthContext));
-    if (boundingBoxSize.isEmpty())
+
+    // Spec: "A negative value is an error. A value of zero disables rendering of the element."
+    if (boundingBoxSize.isZero() || boundingBoxSize.width() < 0 || boundingBoxSize.height() < 0)
         return;
 
     m_fillBoundingBox = FloatRect(FloatPoint(rect->x()->currentValue()->value(lengthContext), rect->y()->currentValue()->value(lengthContext)), boundingBoxSize);
 
     // To decide if the stroke contains a point we create two rects which represent the inner and
     // the outer stroke borders. A stroke contains the point, if the point is between them.
     m_innerStrokeRect = m_fillBoundingBox;
     m_outerStrokeRect = m_fillBoundingBox;
 
     if (style()->svgStyle()->hasStroke()) {
@@ skipping 42 matching lines @@
 }
 
 bool RenderSVGRect::shapeDependentFillContains(const FloatPoint& point, const WindRule fillRule) const
 {
     if (m_usePathFallback)
         return RenderSVGShape::shapeDependentFillContains(point, fillRule);
     return m_fillBoundingBox.contains(point.x(), point.y());
 }
 
 }