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
DimensionValue effectWidth = handle.getEffectiveWidth( );
		DimensionValue effectHeight = handle.getEffectiveHeight( );
		DimensionType width = null;
		DimensionType height = null;
		if ( effectWidth != null )
		{
			width = new DimensionType( effectWidth.getMeasure( ), effectWidth
					.getUnits( ) );
		}
		if ( effectHeight != null )
		{
			height = new DimensionType( effectHeight.getMeasure( ),
					effectHeight.getUnits( ) );
		}
		page.setPageSize( width, height );
		page.setOrientation( handle.getOrientation( ) );
		
		DimensionType top = createDimension( handle.getTopMargin( ) );
		DimensionType left = createDimension( handle.getLeftMargin( ) );
		DimensionType bottom = createDimension( handle.getBottomMargin( ) );
		DimensionType right = createDimension( handle.getRightMargin( ) );
		page.setMargin( top, left, bottom, right );
	}
	protected void visitDesignElement( DesignElementHandle obj )
	{
		
		currentElement = null;
	}
	public void visitGraphicMasterPage( GraphicMasterPageHandle handle )
	{