Use effective columns when cells with colspan are present.

Source/modules/accessibility/AXTableCell.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 178 matching lines @@
 
     rowRange.first += rowOffset;
 }
 
 void AXTableCell::columnIndexRange(pair<unsigned, unsigned>& columnRange)
 {
     if (!m_renderer || !m_renderer->isTableCell())
         return;
 
     LayoutTableCell* cell = toLayoutTableCell(m_renderer);
-    columnRange.first = cell->col();
-    columnRange.second = cell->colSpan();
+    columnRange.first = cell->table()->colToEffCol(cell->col());
+    columnRange.second = cell->table()->colToEffCol(cell->col() + cell->colSpan()) - columnRange.first;
 }
 
 SortDirection AXTableCell::sortDirection() const
 {
     if (roleValue() != RowHeaderRole
         && roleValue() != ColumnHeaderRole)
         return SortDirectionUndefined;
 
     const AtomicString& ariaSort = getAttribute(aria_sortAttr);
     if (ariaSort.isEmpty())
@@ skipping 40 matching lines @@
         return 0;
 
     Node* cellElement = headerCell->node();
     if (!cellElement || !cellElement->hasTagName(thTag))
         return 0;
 
     return axObjectCache()->getOrCreate(headerCell);
 }
 
 } // namespace blink