LayoutTable: gracefully degrade in the presence of collspan > 1.

third_party/WebKit/Source/core/layout/LayoutTable.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, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 243 matching lines @@
 
     unsigned lastEffectiveColumnIndex() const { return numEffectiveColumns() - 1; }
 
     void splitEffectiveColumn(unsigned index, unsigned firstSpan);
     void appendEffectiveColumn(unsigned span);
     unsigned numEffectiveColumns() const { return m_effectiveColumns.size(); }
     unsigned spanOfEffectiveColumn(unsigned effectiveColumnIndex) const { return m_effectiveColumns[effectiveColumnIndex].span; }
 
     unsigned absoluteColumnToEffectiveColumn(unsigned absoluteColumnIndex) const
     {
-        if (!m_hasCellColspanThatDeterminesTableWidth)
+        if (absoluteColumnIndex < m_noCellColspanAtLeast)
             return absoluteColumnIndex;
 
-        unsigned effectiveColumn = 0;
+        unsigned effectiveColumn = m_noCellColspanAtLeast;
         unsigned numColumns = numEffectiveColumns();
-        for (unsigned c = 0; effectiveColumn < numColumns && c + m_effectiveColumns[effectiveColumn].span - 1 < absoluteColumnIndex; ++effectiveColumn)
+        for (unsigned c = m_noCellColspanAtLeast; effectiveColumn < numColumns && c + m_effectiveColumns[effectiveColumn].span - 1 < absoluteColumnIndex; ++effectiveColumn)
             c += m_effectiveColumns[effectiveColumn].span;
         return effectiveColumn;
     }
 
     unsigned effectiveColumnToAbsoluteColumn(unsigned effectiveColumnIndex) const
     {
-        if (!m_hasCellColspanThatDeterminesTableWidth)
+        if (effectiveColumnIndex < m_noCellColspanAtLeast)
             return effectiveColumnIndex;
 
-        unsigned c = 0;
-        for (unsigned i = 0; i < effectiveColumnIndex; i++)
+        unsigned c = m_noCellColspanAtLeast;
+        for (unsigned i = m_noCellColspanAtLeast; i < effectiveColumnIndex; i++)
             c += m_effectiveColumns[i].span;
         return c;
     }
 
     LayoutUnit borderSpacingInRowDirection() const
     {
         if (unsigned effectiveColumnCount = numEffectiveColumns())
             return static_cast<LayoutUnit>(effectiveColumnCount + 1) * hBorderSpacing();
 
         return LayoutUnit();
@@ skipping 194 matching lines @@
     // row groups, column, column groups and table. Thus we cache them in this
     // field.
     CollapsedBorderValues m_collapsedBorders;
     bool m_collapsedBordersValid : 1;
 
     mutable bool m_hasColElements : 1;
     mutable bool m_needsSectionRecalc : 1;
 
     bool m_columnLogicalWidthChanged : 1;
     mutable bool m_columnLayoutObjectsValid: 1;
-    mutable bool m_hasCellColspanThatDeterminesTableWidth : 1;
-    bool hasCellColspanThatDeterminesTableWidth() const
+    mutable unsigned m_noCellColspanAtLeast;
+    unsigned calcNoCellColspanAtLeast() const
     {
         for (unsigned c = 0; c < numEffectiveColumns(); c++) {
             if (m_effectiveColumns[c].span > 1)
-                return true;
+                return c;
         }
-        return false;
+        return numEffectiveColumns();
     }
 
     short m_hSpacing;
     short m_vSpacing;
     int m_borderStart;
     int m_borderEnd;
 };
 
 inline LayoutTableSection* LayoutTable::topSection() const
 {
     ASSERT(!needsSectionRecalc());
     if (m_head)
         return m_head;
     if (m_firstBody)
         return m_firstBody;
     return m_foot;
 }
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutTable, isTable());
 
 } // namespace blink
 
 #endif // LayoutTable_h