Bug 199834 Enable access to IContent object in IReportItemPresentation layer
In IReportItemPresentation layer, the extended item may want to access properties from current IContent object, for example, bookmark, content style. So we need expose the content object in this layer.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/presentation/LocalizedContentVisitor.java
String captionKey = table.getCaptionKey( );
		captionText = localize( table, captionKey, captionText );
		table.setCaption( captionText );
		
		return table;
	}
	public Object visitRow( IRowContent row, Object value )
	{
		handleOnRender( row );
		return row;
	}
	public Object visitCell( ICellContent cell, Object value )
	{
		handleOnRender( cell );
		return cell;
	}
	/**
	 * handle the data content.
	 * 
	 * @param data
	 *            data content object
	 */
	public Object visitData( IDataContent data, Object value )
	{
		handleOnRender( data );
		processData( data );
		return data;
	}
	/**
	 * process the data content