Change PaintLayer::m_layoutObject to a reference.

third_party/WebKit/Source/core/paint/FilterPainter.h

 // Copyright 2014 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 FilterPainter_h
 #define FilterPainter_h
 
 #include "core/paint/PaintLayerPaintingInfo.h"
 #include "wtf/Allocator.h"
 #include <memory>
@@ skipping 15 matching lines @@
                 const LayoutPoint& offsetFromRoot,
                 const ClipRect&,
                 PaintLayerPaintingInfo&,
                 PaintLayerFlags paintFlags);
   ~FilterPainter();
 
  private:
   bool m_filterInProgress;
   GraphicsContext& m_context;
   std::unique_ptr<LayerClipRecorder> m_clipRecorder;
-  LayoutObject* m_layoutObject;
+  LayoutObject& m_layoutObject;
 };
 
 }  // namespace blink
 
 #endif  // FilterPainter_h