Col width is not honored when dynamically updated and it would not make table narrower

Source/core/rendering/RenderTableCol.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 39 matching lines @@
     RenderBox::trace(visitor);
 }
 
 void RenderTableCol::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
     RenderBox::styleDidChange(diff, oldStyle);
 
     // If border was changed, notify table.
     if (parent()) {
         RenderTable* table = this->table();
-        if (table && !table->selfNeedsLayout() && !table->normalChildNeedsLayout() && oldStyle && oldStyle->border() != style()->border())
+        if (table && !table->selfNeedsLayout() && !table->normalChildNeedsLayout() && oldStyle && oldStyle->border() != style()->border()) {
             table->invalidateCollapsedBorders();
+        } else if (oldStyle && oldStyle->logicalWidth() != style()->logicalWidth()) {
+            // FIXME : setPreferredLogicalWidthsDirty is done for all cells as of now.
+            // Need to find a better way so that only the cells which are changed by
+            // the col width should have preferred logical widths recomputed.
+            for (RenderObject* child = table->children()->firstChild(); child; child = child->nextSibling()) {
+                if (child->isTableCaption() || !child->isTableSection())

[mstensho (USE GERRIT), 2015/01/13 08:34:47]

A caption isn't a section, so why bother checking? "if
(!child->isTableSection())" should be enough.

+                    continue;
+                RenderTableSection* section = toRenderTableSection(child);
+                for (RenderTableRow* row = section->firstRow(); row; row = row->nextRow()) {
+                    for (RenderTableCell* cell = row->firstCell(); cell; cell = cell->nextCell())
+                        cell->setPreferredLogicalWidthsDirty();
+                }
+            }
+        }
     }
 }
 
 void RenderTableCol::updateFromElement()
 {
     unsigned oldSpan = m_span;
     Node* n = node();
     if (isHTMLTableColElement(n)) {
         HTMLTableColElement& tc = toHTMLTableColElement(*n);
         m_span = tc.span();
@@ skipping 108 matching lines @@
     return style()->borderStart();
 }
 
 const BorderValue& RenderTableCol::borderAdjoiningCellAfter(const RenderTableCell* cell) const
 {
     ASSERT_UNUSED(cell, table()->colElement(cell->col() - 1) == this);
     return style()->borderEnd();
 }
 
 }