Update documentation and cleanup impls for localToSVGParentTransform()

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
index 0334e0451cb9a8dda061ed26e77323ed82dd79f3..3f59a14bcd1dd0f11dfa874faddc4df6584f2197 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
@@ -342,17 +342,10 @@ void LayoutSVGRoot::buildLocalToBorderBoxTransform() {
   m_localToBorderBoxTransform.preMultiply(viewToBorderBoxTransform);
 }
 
-const AffineTransform& LayoutSVGRoot::localToSVGParentTransform() const {
-  // Slightly optimized version of m_localToParentTransform =
-  // AffineTransform::translation(x(), y()) * m_localToBorderBoxTransform;
-  m_localToParentTransform = m_localToBorderBoxTransform;
-  if (location().x())
-    m_localToParentTransform.setE(m_localToParentTransform.e() +
-                                  roundToInt(location().x()));
-  if (location().y())
-    m_localToParentTransform.setF(m_localToParentTransform.f() +
-                                  roundToInt(location().y()));
-  return m_localToParentTransform;
+AffineTransform LayoutSVGRoot::localToSVGParentTransform() const {
+  return AffineTransform::translation(roundToInt(location().x()),
+                                      roundToInt(location().y())) *
+         m_localToBorderBoxTransform;
 }
 
 LayoutRect LayoutSVGRoot::localVisualRect() const {