Fix caret paint invalidation when moving between blocks

third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 73 matching lines @@
   }
   void paintCaret(GraphicsContext&,
                   const LayoutPoint& paintOffset,
                   DisplayItem::Type) const;
 
   // DisplayItemClient methods.
   LayoutRect visualRect() const final;
   String debugName() const final;
 
  private:
+  void invalidatePaintInCurrentLayoutBlock(
+      const PaintInvalidatorContext&,
+      PaintInvalidationReason layoutBlockPaintInvalidationReason);
+
+  void invalidatePaintInPreviousLayoutBlock(
+      const PaintInvalidatorContext&,
+      PaintInvalidationReason layoutBlockPaintInvalidationReason);
+
   // These are updated by updateStyleAndLayoutIfNeeded().
   Color m_color;
   LayoutRect m_localRect;
   LayoutBlock* m_layoutBlock = nullptr;
 
-  // This is set to the previous m_layoutBlock if m_layoutLayout will change
-  // during updateStyleAndLayoutIfNeeded() and can be used in
-  // invalidatePaintIfNeeded() only.
+  // This is set to the previous value of m_layoutBlock during
+  // updateStyleAndLayoutIfNeeded() and can be used in invalidatePaintIfNeeded()
+  // only.
   const LayoutBlock* m_previousLayoutBlock = nullptr;
 
-  // This is updated by invalidatePaintIfNeeded().
+  // Visual rect of the caret in m_layoutBlock. This is updated by
+  // invalidatePaintIfNeeded().
   LayoutRect m_visualRect;
 
+  // This is set to the previous value of m_visualRect during
+  // updateStyleAndLayoutIfNeeded() and can be used in invalidatePaintIfNeeded()
+  // only.
+  LayoutRect m_previousVisualRect;
+
   bool m_needsPaintInvalidation = false;
 };
 
 }  // namespace blink
 
 #endif  // CaretDisplayItemClient_h