Remove unused PaintInvalidationState::renderer()

Source/core/rendering/PaintInvalidationState.h

Index: Source/core/rendering/PaintInvalidationState.h
diff --git a/Source/core/rendering/PaintInvalidationState.h b/Source/core/rendering/PaintInvalidationState.h
index d7dcd2ec013cbe87cebd3e781d14096a6a48da7f..d32fd7a265b454c434b380e4d3dd1c0288ad2293 100644
--- a/Source/core/rendering/PaintInvalidationState.h
+++ b/Source/core/rendering/PaintInvalidationState.h
@@ -34,7 +34,6 @@ public:
     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
     {
@@ -55,8 +54,6 @@ private:
     LayoutSize m_paintOffset;
 
     const RenderLayerModelObject& m_paintInvalidationContainer;
-
-    const RenderObject& m_renderer;
 };
 
 } // namespace blink