Made varied number of cells in each row based on row's requirement.

third_party/WebKit/Source/core/layout/LayoutTableSection.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, 2013 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 200 matching lines @@
   const LayoutTableCell* firstRowCellAdjoiningTableStart() const;
   const LayoutTableCell* firstRowCellAdjoiningTableEnd() const;
 
   CellStruct& cellAt(unsigned row, unsigned effectiveColumn) {
     return m_grid[row].row[effectiveColumn];
   }
   const CellStruct& cellAt(unsigned row, unsigned effectiveColumn) const {
     return m_grid[row].row[effectiveColumn];
   }
   LayoutTableCell* primaryCellAt(unsigned row, unsigned effectiveColumn) {
+    if (effectiveColumn >= numCols(row))
+      return nullptr;
     CellStruct& c = m_grid[row].row[effectiveColumn];
     return c.primaryCell();
   }
   const LayoutTableCell* primaryCellAt(unsigned row,
                                        unsigned effectiveColumn) const {
     return const_cast<LayoutTableSection*>(this)->primaryCellAt(
         row, effectiveColumn);
   }
 
+  unsigned numCols(unsigned row) const { return m_grid[row].row.size(); }
+
   // Returns null for cells with a rowspan that exceed the last row. Possibly
   // others.
   LayoutTableRow* rowLayoutObjectAt(unsigned row) {
     return m_grid[row].rowLayoutObject;
   }
   const LayoutTableRow* rowLayoutObjectAt(unsigned row) const {
     return m_grid[row].rowLayoutObject;
   }
 
   void appendEffectiveColumn(unsigned pos);
@@ skipping 100 matching lines @@
   void willBeRemovedFromTree() override;
 
   void layout() override;
 
   int borderSpacingForRow(unsigned row) const {
     return m_grid[row].rowLayoutObject ? table()->vBorderSpacing() : 0;
   }
 
   void ensureRows(unsigned);
 
+  void ensureCol(unsigned r, unsigned c) {

[mstensho (USE GERRIT), 2017/01/03 15:18:41]

Maybe it should be named ensureCols(), since we already have ensureRows()? Also,
I wonder if the "c" parameter should be column count, rather than column index,
since ensureRows() takes row count, not row index. And how about more
descriptive parameter names, such as rowIndex and numCols?

[a.suchit, 2017/01/04 10:35:18]

Done.

+    if (c >= numCols(r))
+      m_grid[r].row.grow(c + 1);
+  }
+
   bool rowHasOnlySpanningCells(unsigned);
   unsigned calcRowHeightHavingOnlySpanningCells(unsigned,
                                                 int&,
                                                 unsigned,
                                                 unsigned&,
                                                 Vector<int>&);
   void updateRowsHeightHavingOnlySpanningCells(LayoutTableCell*,
                                                struct SpanningRowsHeight&,
                                                unsigned&,
                                                Vector<int>&);
@@ skipping 103 matching lines @@
   // The use is to disable a painting optimization where we just paint the
   // invalidated cells.
   bool m_hasMultipleCellLevels;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutTableSection, isTableSection());
 
 }  // namespace blink
 
 #endif  // LayoutTableSection_h