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 33 matching lines @@
     updateFromElement();
 }
 
 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()) {
+            unsigned nEffCols = table->numEffCols();
+            unsigned currentColumn = 0;
+            RenderTableSection* section = 0;
+            for (RenderTableCol* column = table->firstColumn()->nextColumn(); column; column = column->nextColumn()) {
+                if (this == column)
+                    break;
+                currentColumn += column->span();
+            }
+            for (RenderObject* child = table->firstChild(); child; child = child->nextSibling()) {
+                if (child->isTableSection()) {
+                    section = toRenderTableSection(child);
+                    break;
+                }
+            }

[Julien - ping for review, 2014/02/24 19:25:31]

There is table->topSection() that will give you this answer in a more optimized
manner.

[Gurpreet, 2014/02/25 13:12:56]

Done.

+            unsigned currentColSpan = currentColumn + span();
+            for (unsigned j = currentColumn; j < currentColSpan && currentColSpan <= nEffCols; j++) {
+                for (unsigned i = 0; i < section->numRows(); i++) {
+                    RenderTableCell* cell = section->primaryCellAt(i, j);
+                    if (!cell)
+                        continue;
+                    cell->setPreferredLogicalWidthsDirty();
+                }
+            }
+        }

[Julien - ping for review, 2014/02/24 19:25:31]

Again, you need to invalidate the whole column which spans several sections so
doing that for the first section just doesn't work.

[Gurpreet, 2014/02/25 13:12:56]

Done.

     }
 }
 
 void RenderTableCol::updateFromElement()
 {
     unsigned oldSpan = m_span;
     Node* n = node();
     if (n && (n->hasTagName(colTag) || n->hasTagName(colgroupTag))) {
         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();
 }
 
 }