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
* 
	 * @return FPE's IR.
	 */
	public Report translate( )
	{
		report = new Report( );
		report.setReportDesign( handle );
		apply( handle );
		return report;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.DesignVisitor#visitReportDesign(org.eclipse.birt.report.model.api.ReportDesignHandle)
	 */
	public void visitReportDesign( ReportDesignHandle handle )
	{
		report.setUnit( handle.getDefaultUnits( ) );
		if ( handle.getBase( ) != null && !handle.getBase( ).equals( "" ) ) 
		{
			report.setBasePath( handle.getBase( ) );
		}
		defaultUnit = report.getUnit( );
		
		
		setupNamedExpressions( handle, 
				report.getNamedExpressions( ) );