void LayoutTableCol::styleDidChange(StyleDifference diff, const ComputedStyle* oldStyle)
{
    LayoutBox::styleDidChange(diff, oldStyle);

    // If border was changed, notify table.
    if (parent()) {
        LayoutTable* table = this->table();
        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 (LayoutObject* child = table->children()->firstChild(); child; child = child->nextSibling()) {
                if (!child->isTableSection())
                    continue;
                LayoutTableSection* section = toLayoutTableSection(child);
                for (LayoutTableRow* row = section->firstRow(); row; row = row->nextRow()) {
                    for (LayoutTableCell* cell = row->firstCell(); cell; cell = cell->nextCell())
                        cell->setPreferredLogicalWidthsDirty();
                }
            }
        }
    }
}
void TableLayoutAlgorithmFixed::willChangeTableLayout()
{
    // When switching table layout algorithm, we need to dirty the preferred
    // logical widths as we cleared the bits without computing them.
    // (see calcWidthArray above.) This optimization is preferred to always
    // computing the logical widths we never intended to use.
    m_table->recalcSectionsIfNeeded();
    for (LayoutTableSection* section = m_table->topNonEmptySection(); section; section = m_table->sectionBelow(section)) {
        for (unsigned i = 0; i < section->numRows(); i++) {
            LayoutTableRow* row = section->rowLayoutObjectAt(i);
            if (!row)
                continue;
            for (LayoutTableCell* cell = row->firstCell(); cell; cell = cell->nextCell())
                cell->setPreferredLogicalWidthsDirty();
        }
    }
}