Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
Iterator visibilityIter = handle.visibilityRulesIterator( );
		VisibilityDesign visibility = createVisibility( visibilityIter );
		item.setVisibility( visibility );
	}
	/**
	 * setup report element attribute
	 * 
	 * @param elem
	 *            engine's report element
	 * @param handle
	 *            DE's report element
	 */
	private void setupReportElement( ReportElementDesign element,
			DesignElementHandle handle )
	{
		element.setHandle( handle );
		element.setName( handle.getName( ) );
		element.setID( handle.getID( ) );
		DesignElementHandle extend = handle.getExtends( );
		if ( extend != null )
		{
			element.setExtends( extend.getName( ) );
		}
		
		Iterator iter = handle.getPropertyIterator( );
		if ( iter != null )
		{
			PropertyHandle propHandle = (PropertyHandle) iter.next( );
			if ( propHandle != null && propHandle.isSet( ) )
			{