Don't always invalidate collapsed borders during table layout

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

Index: third_party/WebKit/Source/core/layout/LayoutTable.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutTable.h b/third_party/WebKit/Source/core/layout/LayoutTable.h
index 7d0ffa078a7cbd2a620cd2a3d3a513cbc42e709f..a803b6f9efd7f44136230548ae6626e9e9b9c967 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTable.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTable.h
@@ -392,6 +392,10 @@ class CORE_EXPORT LayoutTable final : public LayoutBlock {
     needs_section_recalc_ = true;
     SetNeedsLayoutAndFullPaintInvalidation(
         LayoutInvalidationReason::kTableChanged);
+
+    // Grid structure affects cell adjacence relationships which affect
+    // conflict resolution of collapsed borders.
+    InvalidateCollapsedBorders();
   }
 
   LayoutTableSection* SectionAbove(
@@ -406,7 +410,11 @@ class CORE_EXPORT LayoutTable final : public LayoutBlock {
   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(); }
@@ -436,11 +444,6 @@ class CORE_EXPORT LayoutTable final : public LayoutBlock {
 
   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;