[SVG] Fix root element length values handling.

Source/core/svg/graphics/filters/SVGFEImage.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
  * Copyright (C) 2005 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2010 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2013 Google 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
@@ skipping 103 matching lines @@
     IntPoint paintLocation = absolutePaintRect().location();
     destRect.move(-paintLocation.x(), -paintLocation.y());
 
     // FEImage results are always in ColorSpaceDeviceRGB
     setResultColorSpace(ColorSpaceDeviceRGB);
 
     if (renderer) {
         SVGElement* contextNode = toSVGElement(renderer->node());
         if (contextNode->hasRelativeLengths()) {
             SVGLengthContext lengthContext(contextNode);
-            float width = 0;
-            float height = 0;
+            FloatSize viewportSize;
 
             // If we're referencing an element with percentage units, eg. <rect with="30%"> those values were resolved against the viewport.
             // Build up a transformation that maps from the viewport space to the filter primitive subregion.
-            if (lengthContext.determineViewport(width, height))
-                resultImage->context()->concatCTM(makeMapBetweenRects(FloatRect(0, 0, width, height), destRect));
+            if (lengthContext.determineViewport(viewportSize))
+                resultImage->context()->concatCTM(makeMapBetweenRects(FloatRect(FloatPoint(), viewportSize), destRect));
         } else {
             const AffineTransform& absoluteTransform = filter()->absoluteTransform();
             resultImage->context()->concatCTM(absoluteTransform);
         }
 
         AffineTransform contentTransformation;
         SVGRenderingContext::renderSubtree(resultImage->context(), renderer, contentTransformation);
         return;
     }
 
@@ skipping 20 matching lines @@
     if (!m_image)
         return 0;
 
     if (!m_image->nativeImageForCurrentFrame())
         return 0;
 
     return adoptRef(new SkBitmapSource(m_image->nativeImageForCurrentFrame()->bitmap()));
 }
 
 } // namespace WebCore