Don't always invalidate collapsed borders during table layout

third_party/WebKit/Source/core/layout/LayoutTable.h

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009, 2010 Apple Inc.
  *               All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 374 matching lines @@
       return;
     // For all we know, sections may have been deleted at this point. Don't
     // keep pointers dangling around.
     head_ = nullptr;
     foot_ = nullptr;
     first_body_ = nullptr;
 
     needs_section_recalc_ = true;
     SetNeedsLayoutAndFullPaintInvalidation(
         LayoutInvalidationReason::kTableChanged);
+
+    // Grid structure affects cell adjacence relationships which affect
+    // conflict resolution of collapsed borders.
+    InvalidateCollapsedBorders();
   }
 
   LayoutTableSection* SectionAbove(
       const LayoutTableSection*,
       SkipEmptySectionsValue = kDoNotSkipEmptySections) const;
   LayoutTableSection* SectionBelow(
       const LayoutTableSection*,
       SkipEmptySectionsValue = kDoNotSkipEmptySections) const;
 
   LayoutTableCell* CellAbove(const LayoutTableCell*) const;
   LayoutTableCell* CellBelow(const LayoutTableCell*) const;
   LayoutTableCell* CellBefore(const LayoutTableCell*) const;
   LayoutTableCell* CellAfter(const LayoutTableCell*) const;
 
-  typedef Vector<CollapsedBorderValue> CollapsedBorderValues;
+  using CollapsedBorderValues = Vector<CollapsedBorderValue>;
+  const CollapsedBorderValues& CollapsedBorders() const {
+    DCHECK(collapsed_borders_valid_);
+    return collapsed_borders_;
+  }
   void InvalidateCollapsedBorders();
 
   bool HasSections() const { return Header() || Footer() || FirstBody(); }
 
   void RecalcSectionsIfNeeded() const {
     if (needs_section_recalc_)
       RecalcSections();
   }
 
   static LayoutTable* CreateAnonymousWithParent(const LayoutObject*);
   LayoutBox* CreateAnonymousBoxWithSameTypeAs(
       const LayoutObject* parent) const override {
     return CreateAnonymousWithParent(parent);
   }
 
   const BorderValue& TableStartBorderAdjoiningCell(
       const LayoutTableCell*) const;
   const BorderValue& TableEndBorderAdjoiningCell(const LayoutTableCell*) const;
 
   void AddCaption(const LayoutTableCaption*);
   void RemoveCaption(const LayoutTableCaption*);
   void AddColumn(const LayoutTableCol*);
   void RemoveColumn(const LayoutTableCol*);
 
   void PaintBoxDecorationBackground(const PaintInfo&,
                                     const LayoutPoint&) const final;
 
   void PaintMask(const PaintInfo&, const LayoutPoint&) const final;
 
-  const CollapsedBorderValues& CollapsedBorders() const {
-    DCHECK(collapsed_borders_valid_);
-    return collapsed_borders_;
-  }
-
   void SubtractCaptionRect(LayoutRect&) const;
 
   bool IsLogicalWidthAuto() const;
 
   // When table headers are repeated, we need to know the offset from the block
   // start of the fragmentation context to the first occurrence of the table
   // header.
   LayoutUnit BlockOffsetToFirstRepeatableHeader() const {
     return block_offset_to_first_repeatable_header_;
   }
@@ skipping 163 matching lines @@
   if (first_body_)
     return first_body_;
   return foot_;
 }
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutTable, IsTable());
 
 }  // namespace blink
 
 #endif  // LayoutTable_h