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

third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp

Index: third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp b/third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp
index 451ef102c1ef1d08828139d20148ca580a492924..71a5c331b26f56858c4d7a61362f05da3ef0f193 100644
--- a/third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp
+++ b/third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp
@@ -48,8 +48,8 @@ FEDisplacementMap* FEDisplacementMap::create(Filter* filter, ChannelSelectorType
 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;
 }