Replace coversExtraPixels with simpler logic

third_party/WebKit/Source/core/paint/BoxPaintInvalidator.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 BoxPaintInvalidator_h
 #define BoxPaintInvalidator_h
 
 #include "platform/graphics/PaintInvalidationReason.h"
 #include "wtf/Allocator.h"
 
@@ skipping 13 matching lines @@
       : m_box(box), m_context(context) {}
 
   static void boxWillBeDestroyed(const LayoutBox&);
 
   PaintInvalidationReason invalidatePaintIfNeeded();
 
  private:
   PaintInvalidationReason computePaintInvalidationReason();
 
   bool incrementallyInvalidatePaint();
-  void invalidatePaintRectClippedByOldAndNewBounds(const LayoutRect&);
 
   bool needsToSavePreviousBoxSizes();
   void savePreviousBoxSizesIfNeeded();
   LayoutSize computePreviousBorderBoxSize(const LayoutSize& previousBoundsSize);
 
   const LayoutBox& m_box;
   const PaintInvalidatorContext& m_context;
 };
 
 }  // namespace blink
 
 #endif