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

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

Index: third_party/WebKit/Source/core/layout/LayoutTableSection.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableSection.h b/third_party/WebKit/Source/core/layout/LayoutTableSection.h
index 916aab9e2f2aa2e4802a97339ac1decc9460a440..ac73b8e7708af6b3c3ce968043856f3897811a89 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableSection.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTableSection.h
@@ -218,6 +218,8 @@ class CORE_EXPORT LayoutTableSection final : public LayoutTableBoxComponent {
     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();
   }
@@ -227,6 +229,8 @@ class CORE_EXPORT LayoutTableSection final : public LayoutTableBoxComponent {
         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) {
@@ -345,7 +349,15 @@ class CORE_EXPORT LayoutTableSection final : public LayoutTableBoxComponent {
     return m_grid[row].rowLayoutObject ? table()->vBorderSpacing() : 0;
   }
 
-  void ensureRows(unsigned);
+  void ensureRows(unsigned numRows) {
+    if (numRows > m_grid.size())
+      m_grid.grow(numRows);
+  }
+
+  void ensureCols(unsigned rowIndex, unsigned numCols) {
+    if (numCols > LayoutTableSection::numCols(rowIndex))

[mstensho (USE GERRIT), 2017/01/04 10:56:06]

Could use this->numCols() instead.

[a.suchit, 2017/01/05 03:34:31]

Done.

+      m_grid[rowIndex].row.grow(numCols);
+  }
 
   bool rowHasOnlySpanningCells(unsigned);
   unsigned calcRowHeightHavingOnlySpanningCells(unsigned,