Remove unused PaintInvalidationState::renderer()

Source/core/rendering/PaintInvalidationState.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 PaintInvalidationState_h
 #define PaintInvalidationState_h
 
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/Noncopyable.h"
 
@@ skipping 16 matching lines @@
     const LayoutRect& clipRect() const { return m_clipRect; }
     const LayoutSize& paintOffset() const { return m_paintOffset; }
 
     bool cachedOffsetsEnabled() const { return m_cachedOffsetsEnabled; }
     bool isClipped() const { return m_clipped; }
 
     bool forceCheckForPaintInvalidation() const { return m_forceCheckForPaintInvalidation; }
     void setForceCheckForPaintInvalidation() { m_forceCheckForPaintInvalidation = true; }
 
     const RenderLayerModelObject& paintInvalidationContainer() const { return m_paintInvalidationContainer; }
-    const RenderObject& renderer() const { return m_renderer; }
 
     bool canMapToContainer(const RenderLayerModelObject* container) const
     {
         return m_cachedOffsetsEnabled && container == &m_paintInvalidationContainer;
     }
 private:
     void applyClipIfNeeded(const RenderObject&);
 
     friend class ForceHorriblySlowRectMapping;
 
     bool m_clipped;
     mutable bool m_cachedOffsetsEnabled;
     bool m_forceCheckForPaintInvalidation;
 
     LayoutRect m_clipRect;
 
     // x/y offset from paint invalidation container. Includes relative positioning and scroll offsets.
     LayoutSize m_paintOffset;
 
     const RenderLayerModelObject& m_paintInvalidationContainer;
-
-    const RenderObject& m_renderer;
 };
 
 } // namespace blink
 
 #endif // PaintInvalidationState_h