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
* 
	 * <li> localize the help text
	 * <li> format the value
	 * <li> handle it as it is an text.
	 * 
	 * @param data
	 *            data object
	 */
	protected void processData( IDataContent data )
	{
		String helpText = localize( data, data.getHelpKey( ), data.getHelpText( ) );
		data.setHelpText( helpText );
		String text = ""; 
		if ( data.getLabelKey( ) != null || data.getLabelText( ) != null )
		{
			text = localize( data, data.getLabelKey( ), data.getLabelText( ) );
		}
		else
		{
			Object value = data.getValue( );
			if ( value instanceof Object[] )
			{
				Object[] values = (Object[]) value;
				if ( values.length > 0 )
				{
					value = values[0];
				}
				else
				{
					value = null;