The span of a table-column or table-column-group should never be 0.

Source/core/layout/LayoutTableCol.cpp

 /*
  * 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 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 60 matching lines @@
 }
 
 void LayoutTableCol::updateFromElement()
 {
     unsigned oldSpan = m_span;
     Node* n = node();
     if (isHTMLTableColElement(n)) {
         HTMLTableColElement& tc = toHTMLTableColElement(*n);
         m_span = tc.span();
     } else {
-        m_span = !(style() && style()->display() == TABLE_COLUMN_GROUP);

[leviw_travelin_and_unemployed, 2015/05/29 17:07:12]

This was just weird to begin with!

+        m_span = 1;
     }
     if (m_span != oldSpan && style() && parent())
         setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation(LayoutInvalidationReason::AttributeChanged);
 }
 
 void LayoutTableCol::insertedIntoTree()
 {
     LayoutBox::insertedIntoTree();
     table()->addColumn(this);
 }
@@ skipping 97 matching lines @@
     return style()->borderStart();
 }
 
 const BorderValue& LayoutTableCol::borderAdjoiningCellAfter(const LayoutTableCell* cell) const
 {
     ASSERT_UNUSED(cell, table()->colElement(cell->col() - 1) == this);
     return style()->borderEnd();
 }
 
 }