Update documentation and cleanup impls for localToSVGParentTransform()

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

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2009 Google, Inc.  All rights reserved.
  * Copyright (C) 2009 Apple 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 103 matching lines @@
   void willBeDestroyed() override;
   void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
   bool isChildAllowed(LayoutObject*, const ComputedStyle&) const override;
   void addChild(LayoutObject* child,
                 LayoutObject* beforeChild = nullptr) override;
   void removeChild(LayoutObject*) override;
 
   void insertedIntoTree() override;
   void willBeRemovedFromTree() override;
 
-  const AffineTransform& localToSVGParentTransform() const override;
+  AffineTransform localToSVGParentTransform() const override;
 
   FloatRect objectBoundingBox() const override { return m_objectBoundingBox; }
   FloatRect strokeBoundingBox() const override { return m_strokeBoundingBox; }
   FloatRect visualRectInLocalSVGCoordinates() const override {
     return m_visualRectInLocalSVGCoordinates;
   }
 
   bool nodeAtPoint(HitTestResult&,
                    const HitTestLocation& locationInContainer,
                    const LayoutPoint& accumulatedOffset,
@@ skipping 23 matching lines @@
   void buildLocalToBorderBoxTransform();
 
   PositionWithAffinity positionForPoint(const LayoutPoint&) final;
 
   LayoutObjectChildList m_children;
   IntSize m_containerSize;
   FloatRect m_objectBoundingBox;
   bool m_objectBoundingBoxValid;
   FloatRect m_strokeBoundingBox;
   FloatRect m_visualRectInLocalSVGCoordinates;
-  mutable AffineTransform m_localToParentTransform;
   AffineTransform m_localToBorderBoxTransform;
   bool m_isLayoutSizeChanged : 1;
   bool m_didScreenScaleFactorChange : 1;
   bool m_needsBoundariesOrTransformUpdate : 1;
   bool m_hasBoxDecorationBackground : 1;
   mutable bool m_hasNonIsolatedBlendingDescendants : 1;
   mutable bool m_hasNonIsolatedBlendingDescendantsDirty : 1;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutSVGRoot, isSVGRoot());
 
 }  // namespace blink
 
 #endif  // LayoutSVGRoot_h