[SPv1] Fix return value for "fallback" case of inverted clips.

third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GeometryMapper_h
 #define GeometryMapper_h
 
 #include "platform/graphics/paint/FloatClipRect.h"
 #include "platform/graphics/paint/PropertyTreeState.h"
 #include "platform/transforms/TransformationMatrix.h"
@@ skipping 120 matching lines @@
   static const TransformationMatrix& LocalToAncestorMatrix(
       const TransformPaintPropertyNode* local_transform_node,
       const TransformPaintPropertyNode* ancestor_transform_node);
 
   // Returns the "clip visual rect" between |localTransformState| and
   // |ancestorState|. See above for the definition of "clip visual rect".
   //
   // The output FloatClipRect may contain false positives for rounded-ness
   // if a rounded clip is clipped out, and overly conservative results
   // in the presences of transforms.
-  static FloatClipRect LocalToAncestorClipRect(
+  static const FloatClipRect& LocalToAncestorClipRect(
       const PropertyTreeState& local_transform_state,
       const PropertyTreeState& ancestor_state);
 
   // Like localToAncestorClipRect, except it can handle destination transform
   // spaces which are not direct ancestors of the source transform space.
   //
   // The output FloatClipRect may contain false positives for rounded-ness
   // if a rounded clip is clipped out, and overly conservative results
   // in the presences of transforms.
   static const FloatClipRect& SourceToDestinationClipRect(
@@ skipping 57 matching lines @@
   static const FloatClipRect& InfiniteClip();
   static FloatClipRect& TempRect();
 
   friend class GeometryMapperTest;
   friend class PaintLayerClipperTest;
 };
 
 }  // namespace blink
 
 #endif  // GeometryMapper_h