Table with fixed layout behaves like auto layout when its width is set by js instead of css.

Source/core/rendering/RenderTable.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, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 72 matching lines @@
     RenderBlock::styleDidChange(diff, oldStyle);
     propagateStyleToAnonymousChildren();
 
     ETableLayout oldTableLayout = oldStyle ? oldStyle->tableLayout() : TAUTO;
 
     // In the collapsed border model, there is no cell spacing.
     m_hSpacing = collapseBorders() ? 0 : style()->horizontalBorderSpacing();
     m_vSpacing = collapseBorders() ? 0 : style()->verticalBorderSpacing();
     m_columnPos[0] = m_hSpacing;
 
-    if (!m_tableLayout || style()->tableLayout() != oldTableLayout) {
+    if (!m_tableLayout || style()->tableLayout() != oldTableLayout || diff.needsFullLayout()) {

[mstensho (USE GERRIT), 2014/05/06 13:28:59]

It seems wrong to recreate the table layout object every time you want to lay
out the table. You only want to do this if it's missing or if you're really
going to switch layout algorithm.

The problem here is the "style()->tableLayout() != oldTableLayout" test. It
doesn't account for the fact that auto width means auto table layout, even if
the specified value of 'table-layout' is 'fixed'.

A helper method (e.g. "isTableLayoutFixed()") in RenderStyle, which checks both
for table-layout:fixed AND non-auto width, could be a better solution. It could
be called both on this line, and on a few lines further below (which already
does the right thing).

         if (m_tableLayout)
             m_tableLayout->willChangeTableLayout();
 
         // According to the CSS2 spec, you only use fixed table layout if an
         // explicit width is specified on the table.  Auto width implies auto table layout.
         if (style()->tableLayout() == TFIXED && !style()->logicalWidth().isAuto())
             m_tableLayout = adoptPtr(new FixedTableLayout(this));
         else
             m_tableLayout = adoptPtr(new AutoTableLayout(this));
     }
@@ skipping 1353 matching lines @@
 const BorderValue& RenderTable::tableEndBorderAdjoiningCell(const RenderTableCell* cell) const
 {
     ASSERT(cell->isFirstOrLastCellInRow());
     if (hasSameDirectionAs(cell->row()))
         return style()->borderEnd();
 
     return style()->borderStart();
 }
 
 }