Traverse into child LayoutViews during invalidateTreeIfNeeded

Source/core/layout/LayoutPart.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2006, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 44 matching lines @@
     virtual void paintContents(const PaintInfo&, const LayoutPoint&);
 
 protected:
     virtual DeprecatedPaintLayerType layerTypeRequired() const override;
 
     virtual void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override final;
     virtual void layout() override;
     virtual void paint(const PaintInfo&, const LayoutPoint&) override;
     virtual CursorDirective getCursor(const LayoutPoint&, Cursor&) const override final;
 
+    // Overridden to invalidate the child frame if any.
+    virtual void invalidatePaintOfSubtreesIfNeeded(PaintInvalidationState&) override;
+
 private:
     virtual CompositingReasons additionalCompositingReasons() const override;
 
     virtual void willBeDestroyed() override final;
     virtual void destroy() override final;
 
     bool setWidgetGeometry(const LayoutRect&);
 
     bool nodeAtPointOverWidget(HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction);
 
     int m_refCount;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutPart, isLayoutPart());
 
 } // namespace blink
 
 #endif // LayoutPart_h