Don't invalidate rect if it's covered by fully invalidated parent's visual rect

third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.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 ObjectPaintInvalidator_h
 #define ObjectPaintInvalidator_h
 
 #include "core/CoreExport.h"
 #include "platform/graphics/PaintInvalidationReason.h"
 #include "wtf/Allocator.h"
@@ skipping 94 matching lines @@
       PaintInvalidationReason);
 
   // This function generates a full invalidation, which means invalidating both
   // |oldVisualRect| and |newVisualRect|.  This is the default choice when
   // generating an invalidation, as it is always correct, albeit it may force
   // some extra painting.
   void fullyInvalidatePaint(PaintInvalidationReason,
                             const LayoutRect& oldVisualRect,
                             const LayoutRect& newVisualRect);
 
+  void invalidatePaintRectangleWithContext(const LayoutRect&,
+                                           PaintInvalidationReason);
+
  private:
   void invalidateSelectionIfNeeded(PaintInvalidationReason);
+  bool parentFullyInvalidatedOnSameBacking();
 
   const PaintInvalidatorContext& m_context;
 };
 
 // TODO(crbug.com/457415): We should not allow paint invalidation out of paint
 // invalidation state.
 class DisablePaintInvalidationStateAsserts {
   STACK_ALLOCATED();
   WTF_MAKE_NONCOPYABLE(DisablePaintInvalidationStateAsserts);
 
  public:
   DisablePaintInvalidationStateAsserts();
 
  private:
   AutoReset<bool> m_disabler;
 };
 
 }  // namespace blink
 
 #endif