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..fcf8844348ff6a274c115fc8b341b33256d87740 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) {
@@ -347,6 +351,11 @@ class CORE_EXPORT LayoutTableSection final : public LayoutTableBoxComponent {
 
   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&,