Fix effect mapping computation for displacement-map w/ negative scale

third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.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) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * 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
@@ skipping 30 matching lines @@
 
 FEDisplacementMap* FEDisplacementMap::create(Filter* filter, ChannelSelectorType xChannelSelector,
     ChannelSelectorType yChannelSelector, float scale)
 {
     return new FEDisplacementMap(filter, xChannelSelector, yChannelSelector, scale);
 }
 
 FloatRect FEDisplacementMap::mapEffect(const FloatRect& rect) const
 {
     FloatRect result = rect;
-    result.inflateX(getFilter()->applyHorizontalScale(m_scale / 2));
-    result.inflateY(getFilter()->applyVerticalScale(m_scale / 2));
+    result.inflateX(getFilter()->applyHorizontalScale(std::abs(m_scale) / 2));
+    result.inflateY(getFilter()->applyVerticalScale(std::abs(m_scale) / 2));
     return result;
 }
 
 FloatRect FEDisplacementMap::mapInputs(const FloatRect& rect) const
 {
     return inputEffect(0)->mapRect(rect);
 }
 
 ChannelSelectorType FEDisplacementMap::xChannelSelector() const
 {
@@ skipping 92 matching lines @@
     FilterEffect::externalRepresentation(ts);
     ts << " scale=\"" << m_scale << "\" "
        << "xChannelSelector=\"" << m_xChannelSelector << "\" "
        << "yChannelSelector=\"" << m_yChannelSelector << "\"]\n";
     inputEffect(0)->externalRepresentation(ts, indent + 1);
     inputEffect(1)->externalRepresentation(ts, indent + 1);
     return ts;
 }
 
 } // namespace blink