Refactor LayoutTableCell::Has(Start|End)BorderAdjoinjingTable() and add test

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

Index: third_party/WebKit/Source/core/layout/LayoutTableCell.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableCell.h b/third_party/WebKit/Source/core/layout/LayoutTableCell.h
index fa4c3bedd16d3db6d4c7a7d322f4ea41913cfbeb..63ae3a63e50478fb200315e992d11f03806e2b95 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableCell.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTableCell.h
@@ -349,6 +349,8 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
                             const LayoutRect& container_rect) const override;
 
  private:
+  friend class LayoutTableCellTest;
+
   bool IsOfType(LayoutObjectType type) const override {
     return type == kLayoutObjectTableCell || LayoutBlockFlow::IsOfType(type);
   }
@@ -381,6 +383,8 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
     SetIntrinsicPaddingAfter(after);
   }
 
+  inline bool IsInStartColumn() const;
+  inline bool IsInEndColumn() const;
   bool HasStartBorderAdjoiningTable() const;
   bool HasEndBorderAdjoiningTable() const;